I'm not sure of this forum's opinion on Reedsy, but I've used it for a lot of different things as I begin my self-publishing journey. You can find various artists on there by genre, read user reviews based on the artists' works, and reach out to them for a quote. I just received my book cover a few weeks ago from someone I chose on there. Granted, it took way longer than it should have, though that was the artist's fault, not the site's, but I really, really love the work. (And to be clear, the reviews on this person discussed how he takes forever sometimes, so I was prepared for this.)
More experienced people here might use a better service, but this worked for me.