Archivo de utilería para cambiar los colores de los bars (statusBar y navigationBar)

MainActivity.kt

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        setContentView(R.layout.activity_main)
        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.main)) { v, insets ->
            val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom)
            insets
        }

        findViewById<TextView>(R.id.text).setOnClickListener {
            startActivity(Intent(this, MainActivity2::class.java))
        }

        /**
        Opcion 1
        Se puede colocar desde el Activity para una modificación solo para esa ventana esto solo aplica si no lo combinan con la 
        segunda forma que mencionare abajo la cual es usando la extensión Application
        **/
        SystemBarsOnDecor.init(
            window = window,
            SystemBarsOnDecor.Colors(
                ContextCompat.getColor(this, R.color.blue),
                ContextCompat.getColor(this, R.color.black)
            )
        )
    }
}

NameApp.kt

class Appp : Application(), Application.ActivityLifecycleCallbacks {
    override fun onCreate() {
        super.onCreate()
        registerActivityLifecycleCallbacks(this)
    }

    override fun onActivityCreated(
        activity: Activity,
        savedInstanceState: Bundle?
    ) {
      /**
      Opcion 2
      Segunda opción es colocarlo desde el Application y de esta forma tomara del tema que tenga relacionado con su XML 
      recuerden que cada Activity puede tener su tema gracias a esto solo la configuración es por theme y no manual como la opción 1
      **/
        activity.window.decorView.post {
            SystemBarsOnDecor.initFromTheme(
                window = activity.window,
                context = activity
            )
        }
    }

    override fun onActivityDestroyed(activity: Activity) {

    }

    override fun onActivityPaused(activity: Activity) {

    }

    override fun onActivityResumed(activity: Activity) {

    }

    override fun onActivitySaveInstanceState(
        activity: Activity,
        outState: Bundle
    ) {

    }

    override fun onActivityStarted(activity: Activity) {

    }

    override fun onActivityStopped(activity: Activity) {

    }
}

SystemBarsOnDecor.kt

@Suppress("DEPRECATION")
object SystemBarsOnDecor {

    private const val STATUS_SCRIM = "statusScrim"
    private const val NAV_SCRIM = "navScrim"

    fun init(window: Window, colors: Colors) {

        WindowCompat.setDecorFitsSystemWindows(window, false)
        window.statusBarColor = Color.TRANSPARENT
        window.navigationBarColor = Color.TRANSPARENT

        val decor = window.decorView as ViewGroup
        val statusScrim = ensureOverlay(decor, STATUS_SCRIM, Gravity.TOP)
        val navScrim = ensureOverlay(decor, NAV_SCRIM, Gravity.BOTTOM)

        ViewCompat.setOnApplyWindowInsetsListener(decor) { _, insets ->
            val sysBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
            val isGestureNav = sysBars.bottom == 0

            (statusScrim.layoutParams as FrameLayout.LayoutParams).apply {
                width = ViewGroup.LayoutParams.MATCH_PARENT
                height = sysBars.top
                gravity = Gravity.TOP
            }.also { statusScrim.layoutParams = it }
            statusScrim.setBackgroundColor(opaque(colors.statusBar))

            (navScrim.layoutParams as FrameLayout.LayoutParams).apply {
                width = ViewGroup.LayoutParams.MATCH_PARENT
                height = if (isGestureNav) 0 else sysBars.bottom
                gravity = Gravity.BOTTOM
            }.also { navScrim.layoutParams = it }
            navScrim.setBackgroundColor(opaque(colors.navigationBar))

            val controller = WindowInsetsControllerCompat(window, window.decorView)
            controller.isAppearanceLightStatusBars = (luminance(colors.statusBar) > 0.5) && true
            controller.isAppearanceLightNavigationBars =
                (luminance(colors.navigationBar) > 0.5) && Build.VERSION.SDK_INT >= 26

            insets
        }

        ViewCompat.requestApplyInsets(decor)
    }

    fun initFromTheme(window: Window, context: Context) {
        val status = resolveInOrder(
            context,
            R.attr.statusBarColor,
            com.google.android.material.R.attr.colorSurface,
            androidx.appcompat.R.attr.colorPrimaryDark,
            androidx.appcompat.R.attr.colorPrimary,
            R.attr.colorBackground
        )
        val nav = resolveInOrder(
            context,
            R.attr.navigationBarColor,
            com.google.android.material.R.attr.colorSurface,
            androidx.appcompat.R.attr.colorBackgroundFloating,
            R.attr.colorBackground
        )

        init(window, Colors(statusBar = status, navigationBar = nav))
    }

    fun updateColors(window: Window, colors: Colors) {
        val decor = window.decorView as ViewGroup
        val statusScrim = decor.findViewWithTag<View>(STATUS_SCRIM)
        val navScrim = decor.findViewWithTag<View>(NAV_SCRIM)
        statusScrim?.setBackgroundColor(opaque(colors.statusBar))
        navScrim?.setBackgroundColor(opaque(colors.navigationBar))

        val controller = WindowInsetsControllerCompat(window, window.decorView)
        controller.isAppearanceLightStatusBars = (luminance(colors.statusBar) > 0.5) && true
        controller.isAppearanceLightNavigationBars =
            (luminance(colors.navigationBar) > 0.5) && Build.VERSION.SDK_INT >= 26
    }

    data class Colors(@ColorInt val statusBar: Int, @ColorInt val navigationBar: Int)

    private fun ensureOverlay(parent: ViewGroup, tag: String, gravity: Int): View {
        parent.findViewWithTag<View>(tag)?.let {
            it.bringToFront()
            it.elevation = 10_000f
            return it
        }
        val overlay = View(parent.context).apply {
            this.tag = tag

            this.elevation = 10_000f
        }
        val lp = FrameLayout.LayoutParams(
            ViewGroup.LayoutParams.MATCH_PARENT, 0, gravity
        )

        parent.addView(overlay, lp)
        overlay.bringToFront()
        return overlay
    }

    private fun opaque(@ColorInt c: Int) = ColorUtils.setAlphaComponent(c, 0xFF)
    private fun luminance(@ColorInt c: Int) = ColorUtils.calculateLuminance(opaque(c))

    @ColorInt
    private fun resolveInOrder(context: Context, @AttrRes vararg attrs: Int): Int {
        val tv = TypedValue()
        for (attr in attrs) {
            if (context.theme.resolveAttribute(attr, tv, true)) {
                return if (tv.resourceId != 0) context.getColor(tv.resourceId) else tv.data
            }
        }

        return 0xFF444444.toInt()
    }
}

themes.xml

<!-- Recuerda que puedes generar varios temas para tu aplicación en este caso solo usare el default y uno más llamado Login. -->
<resources xmlns:tools="http://schemas.android.com/tools">
    <style name="Base.Theme.Prueba5" parent="Theme.Material3.DayNight.NoActionBar">
        <item name="android:statusBarColor">@color/blue</item>
        <item name="android:navigationBarColor">@color/white</item>
    </style>

    <style name="Theme.Prueba5" parent="Base.Theme.Prueba5" />

    <style name="Login" parent="Base.Theme.Prueba5">
        <item name="android:statusBarColor">@color/red</item>
    </style>
</resources>