Used this theme helper to change app then between light and drak manually.

ThemeHelper.kt

object ThemeHelper {
    const val LIGHT_MODE = "light"
    const val DARK_MODE = "dark"
    const val DEFAULT_MODE = "default"
    fun applyTheme(theme: String) {
        when (theme) {
            LIGHT_MODE -> {
                AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO)
            }
            DARK_MODE -> {
                AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES)
            }
            else -> {
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
                    AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_FOLLOW_SYSTEM)
                } else {
                    AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_AUTO_BATTERY)
                }
            }
        }
    }
}