In this example I want to start foreground service, and change text in TextView in MainActivity.

First in Android Studio go to File -> New -> Service -> Service and add a service:

In AndroidManifest.xml add FOREGROUND_SERVICE permission:

<uses-permission android:name="android.permission.FOREGROUND_SERVICE" />
* 22023-04-04 UPDATE *

And service:

<service
	android:name=".MyService"
	android:enabled="true"
	android:exported="true"/>

22023-04-04 * ENDOFUPDATE *

Then in service, in my example that is app\src\main\java\com\milosev\startforegroundserviceandbroadcastreceiver\MyService.kt, override onCreate, and the code so that onCreate looks like:
override fun onCreate() {
	super.onCreate()
	sendBroadcastMessage("test")

	val channelId =
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
			createNotificationChannel("my_service", "My Background Service")
		} else {
			// If earlier version channel ID is not used
			// https://developer.android.com/reference/android/support/v4/app/NotificationCompat.Builder.html#NotificationCompat.Builder(android.content.Context)
			""
		}

	val notificationBuilder = NotificationCompat.Builder(this, channelId)
	val notification = notificationBuilder.setOngoing(true)
		.setContentTitle("test")
		.setContentText("test")
		.setSmallIcon(R.mipmap.ic_launcher)
		.setPriority(1)
		.setCategory(Notification.CATEGORY_SERVICE)
		.build()
	startForeground(101, notification)
}
Where sendBroadcastMessage looks like:
private fun sendBroadcastMessage(message: String) {
	val intent = Intent("")
	intent.putExtra("message", message)
	LocalBroadcastManager.getInstance(this).sendBroadcast(intent)
}
and createNotificationChannel:
@RequiresApi(Build.VERSION_CODES.O)
private fun createNotificationChannel(channelId: String, channelName: String): String {
	val chan = NotificationChannel(
		channelId,
		channelName, NotificationManager.IMPORTANCE_NONE
	)
	chan.lightColor = Color.RED
	chan.lockscreenVisibility = Notification.VISIBILITY_PRIVATE
	val service = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
	service.createNotificationChannel(chan)
	return channelId
}
Now MyService.kt looks like:
package com.milosev.startforegroundserviceandbroadcastreceiver

import android.app.Notification
import android.app.NotificationChannel
import android.app.NotificationManager
import android.app.Service
import android.content.Context
import android.content.Intent
import android.graphics.Color
import android.location.Location
import android.os.Build
import android.os.IBinder
import androidx.annotation.RequiresApi
import androidx.core.app.NotificationCompat
import androidx.localbroadcastmanager.content.LocalBroadcastManager

class MyService : Service() {

    override fun onBind(intent: Intent): IBinder {
        TODO("Return the communication channel to the service.")
    }

    override fun onCreate() {
        super.onCreate()
        sendBroadcastMessage("test")

        val channelId =
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                createNotificationChannel("my_service", "My Background Service")
            } else {
                // If earlier version channel ID is not used
                // https://developer.android.com/reference/android/support/v4/app/NotificationCompat.Builder.html#NotificationCompat.Builder(android.content.Context)
                ""
            }

        val notificationBuilder = NotificationCompat.Builder(this, channelId)
        val notification = notificationBuilder.setOngoing(true)
            .setContentTitle("test")
            .setContentText("test")
            .setSmallIcon(R.mipmap.ic_launcher)
            .setPriority(1)
            .setCategory(Notification.CATEGORY_SERVICE)
            .build()
        startForeground(101, notification)
    }

    @RequiresApi(Build.VERSION_CODES.O)
    private fun createNotificationChannel(channelId: String, channelName: String): String {
        val chan = NotificationChannel(
            channelId,
            channelName, NotificationManager.IMPORTANCE_NONE
        )
        chan.lightColor = Color.RED
        chan.lockscreenVisibility = Notification.VISIBILITY_PRIVATE
        val service = getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
        service.createNotificationChannel(chan)
        return channelId
    }

    private fun sendBroadcastMessage(message: String) {
        val intent = Intent("")
        intent.putExtra("message", message)
        LocalBroadcastManager.getInstance(this).sendBroadcast(intent)
    }
}
In MainActivity.kt in onCreate I have added:
override fun onCreate(savedInstanceState: Bundle?) {
	super.onCreate(savedInstanceState)
	setContentView(R.layout.activity_main)

	val broadCastReceiver = object : BroadcastReceiver() {
		override fun onReceive(contxt: Context?, intent: Intent?) {
			val textView = findViewById<TextView>(R.id.textView)
			textView.text = "test"
		}
	}

	LocalBroadcastManager.getInstance(this)
		.registerReceiver(broadCastReceiver, IntentFilter(""))
}
Button click function should look like:
@RequiresApi(Build.VERSION_CODES.O)
fun startForegroundServiceAndBroadcastReceiverClick(view: View) {
	val intent = Intent(this,MyService::class.java)
	startForegroundService(intent)
}
At the end MainActivity.kt looks like:
package com.milosev.startforegroundserviceandbroadcastreceiver

import android.app.Notification
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.content.IntentFilter
import android.os.Build
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.TextView
import androidx.annotation.RequiresApi
import androidx.localbroadcastmanager.content.LocalBroadcastManager

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val broadCastReceiver = object : BroadcastReceiver() {
            override fun onReceive(contxt: Context?, intent: Intent?) {
                val textView = findViewById<TextView>(R.id.textView)
                textView.text = "test"
            }
        }

        LocalBroadcastManager.getInstance(this)
            .registerReceiver(broadCastReceiver, IntentFilter(""))
    }

    @RequiresApi(Build.VERSION_CODES.O)
    fun startForegroundServiceAndBroadcastReceiverClick(view: View) {
        val intent = Intent(this,MyService::class.java)
        startForegroundService(intent)
    }
}
Please notice in MyService.kt line of code:
val intent = Intent("")
and in MainActivity.kt
LocalBroadcastManager.getInstance(this)
	.registerReceiver(broadCastReceiver, IntentFilter(""))
Otherwise if I want to filter my messages I could instead write MainActivity.kt:
val broadCastReceiver = object : BroadcastReceiver() {
	override fun onReceive(contxt: Context?, intent: Intent?) {
		when (intent?.action) {
			"testFilter" -> {
				val textView = findViewById<TextView>(R.id.textView)
				textView.text = "test"
			}
		}
	}
}

LocalBroadcastManager.getInstance(this)
	.registerReceiver(broadCastReceiver, IntentFilter("testFilter"))
and in MyService.kt:
private fun sendBroadcastMessage(message: String) {
	val intent = Intent("testFilter")
	intent.putExtra("message", message)
	LocalBroadcastManager.getInstance(this).sendBroadcast(intent)
}
2023-04-04 Update:

\app\src\main\AndroidManifest.xml looks like:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools">

    <uses-permission android:name="android.permission.FOREGROUND_SERVICE" />

    <application
        android:allowBackup="true"
        android:dataExtractionRules="@xml/data_extraction_rules"
        android:fullBackupContent="@xml/backup_rules"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/Theme.Startforegroundserviceandbroadcastreceiver"
        tools:targetApi="31">

        <service
            android:name=".MyService"
            android:enabled="true"
            android:exported="true"/>
        <activity
            android:name=".MainActivity"
            android:exported="true">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>
\app\src\main\res\layout\activity_main.xml:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="@+id/btnStart"
        app:layout_constraintEnd_toEndOf="@+id/btnStart"
        app:layout_constraintStart_toStartOf="@+id/btnStart"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/btnStart"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="startForegroundServiceAndBroadcastReceiverClick"
        android:text="@string/start"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        app:layout_constraintVertical_bias="0.726" />

</androidx.constraintlayout.widget.ConstraintLayout>