On Android, you can detect dark mode by checking if the uiMode configuration contains UI_MODE_NIGHT_MASK.
By adding -night resources to your project you can let Android automatically pick the right resources. For example, add a colors.xml file inside a values-night folder to specify night mode colors.
fun Context.isInNightMode(): Boolean {
val nightModeFlags = resources.configuration.uiMode and Configuration.UI_MODE_NIGHT_MASK
return nightModeFlags == Configuration.UI_MODE_NIGHT_YES
}