Im new to the SR community and im on a pc for SR eldenring, its hard for me to quit out on m&k so can i use a macro only for quitting out of the game?

Nop. Quit out it's just muscle memory, so. While you running, you will do it very times and soon you'll accustom with that

I strongly recommend going through game's ruleset, so you can see whats allowed and whats not. (It includes information about macros etc)