I'm aware that I can turn off individual sounds using ctrl + y, but I want to turn off custom sounds uploaded by users. If there is a way I'd love to know, if not I might post in suggestions.

The custom sounds such as grip and win sounds are actually "effects"
So you go to setup>Option and you see "Effect Volume" on the top,Tune it to the left and it will turn off every sound. you cannot turn off only the sounds that are by players,You must turn every sound of the game itself.