I see quite a bit boosted on Mastodon, but I'm not sure where they are all posting from. On Pixelfed I follow photographers, so I see photography.

If youwant to see more art, the first step is to follow artists. Try to search for hashtags related to art forms you're interred in on a large Mastodon instance, and follow relevant users wherever you want to follow them from. Pixelfed might be good if you're not interested in text posts, but make sure you display boosts. Lemmy is not good as most content is invisible.

Once you follow some, for example @davidrevoy@framapiaf.org, you'll see what they boost from around the Fediverse. Artists generally have a decent overview over their sphere of interest, so once the ball starts rolling you'll see content from all over.

I filled my feed up quite nicely with independent musicians very quickly after listening to RadioFreeFedi a little while and following a couple of artists. Their boosts creates a nice little window into the indie music scene.