cool thank u. i use xbox controller also. turtle beach recon its called. its not a bad remote. i'm new to pc so i come across stuff i have no clue what it is

you need big picture to use the steam overlay to change the controls. Otherwise you don't need it if you use the default controller setup.

I use an Xbox 1 controller and do not have to use Big Picture Mode. I can remap buttons using the Xbox app on my computer.

I use Big Picture because I have a Dual Sense. Maybe with other controllers you don't need it but windows has a hard time letting me use it even though it's, supposedly, 100% compatible.
I have to add GoG games to Steam Library because otherwise I can't use the controller without Big Picture.