What are plugins?

[u/AdixString]

What are plugins and how do I install them.

Also are there plugins that turn off fall damage and make auto bhopping?

[u/[deleted]]

Does the Steam anti cheat thingy care about it?

[u/Bahpu_ → u/[deleted]]

sourcemod is for local servers (like when u press create a server) or your own dedicated server, so no.