The only think that I know it´s that when the player press the button to activate the third person, a message appears in the chat box saying "Dynamic Third Person: On | Off". Anyways, I tried searching the addon but i didn´t found it.
https://imgur.com/a/3roB2qW | https://imgur.com/a/fDO1GRo
So... If someone knows where I can find this addon, I will appreciatte so much!!
Garry's Mod Leaks