Is there no notification light on your phone? This application is ideal for you

There is a app 'LED Blinker'

link:- https://play.google.com/store/apps/details?id=com.ledblinker

Controls the LED for Facebook, Whatsapp, and other social media platforms. The screen is utilised if you don't have any hardware leds. In the complete version, all apps are supported.

This programme is really easy to use and requires very little configuration!