Thank you for your kind reply but my question is different.
Until the version 8.4.19 I could use the app "Light manager 2" to have the flashing of different color LEDs for each type of notification (Facebook = cyano, Whatsapp = white, Telegram = pink, low battery = red, battery charging = yellow , etc.).
Since the version 8.4.26, has granted the app the necessary permissions, the LED flashes only with the default color for notifications.