Upwork, freelancer, fiver are all gig websites you could use, since it’s a hobby project that’s probably your best bet.
Alternatively design discords might help, make sure to let them know it’s paid.

If you’re looking for more premium then look for specific designers/web devs outside of these places.

Designer here. You could try searching for communities on the fediverse dedicated to design/web design/3D/etc and contacting someone if you like their work or just making a post about it if allowed, or a mastodon/microblog post with lots of related hashtags. Or if you really wanna widen the net, you can try looking on Twitter/Threads/Dribbble/etc. for people you like and contacting them.