Is there such platform like Solo Learn to learn C language and AVR microcontroller?

Answer 1

There is no such type of AVR MicroController simulated plateform with C language.
But you can learn C Language in SoloLearn.
Here is the video for software with coding to work on AVR MCs on laptop/pc.
https://youtu.be/9jqqb5tDvHo
To learn more about AVR microcontrollers try these website:
http://microcontrollerslab.com/avr-microcontroller-tutorials/

Answer 2

he means for microcontroller specially !

Answer 3

There are Sololearn for learning C language