used here https://medium.com/@themukeshsolanki/demystifying-datastore-a-comprehensive-guide-to-using-datastore-with-jetpack-compose-d89c813232d7

PreferenceDataStore.kt

// Define a DataStore for user preferences
val dataStore: DataStore<Preferences> = context.createDataStore(name = "user_preferences")

// Define a key for the dark mode
val DARK_MODE_KEY = booleanPreferencesKey("dark_mode")

// Function to store the toggle value
suspend fun storeDarkMode(isOn: Boolean) {
    dataStore.edit { preferences ->
        preferences[DARK_MODE_KEY] = isOn
    }
}

// Function to retrieve the dark mode value
val darkModeFlow: Flow<Boolean?> = dataStore.data.map { preferences ->
    preferences[DARK_MODE_KEY]
}