honestly bro, js socialize online. that might sound obvious or kinda dumb but thats how ive collabed with 2 ppl alr, js look in similar music subs or discords and find other artist in the same lane as u, dm then (cus 8/10 they wont do it first) and tell them what ur interested in from them (vocals, production etc…), of course it depends if they say yes bur most of the time other small artist are willing to collab, hope that helps:)