Well, you can always go look up people who work in audio and music on Fiverr. Far as I know this is an easy place to navigate and search for people working in specific fields. It's not free, but there's people that are incredibly generous with their services and prices as well as professionals who know exactly what they're doing. You'd really be getting your money's worth on there, I feel. I haven't used the site, but I plan to sometime in the future.
https://www.fiverr.com/categories/music-audio?source=category_tree
If you're really strapped for cash, you could also look on the Newgrounds forums. You might find people willing to work without being paid there. I can't tell you whether or not collabs are successful over there, I haven't really used the site in years, but I know there's a bunch of creators on there.
https://www.newgrounds.com/bbs/forum/19/1
As for as YouTube goes, maybe you could look up demo reels for singers, composers, sound designers and just try to contact them if their information's available?? This would be my last resort though, going around and looking for help like that is just seems kinda.. desperate? Not a good look imo lol
You'd be right. Even if there are people that could be swayed into working with you for free, the project has to be able to stand on its own before they might even consider taking on the job. Real talk, audio is only complementary and the work that goes into it is unreal sometimes for what comes out of it. But if that stuff reeeally matters that much to you, it's never too late to find ways to do the work yourself without paying anything.