

Plexamp does a pretty good job with the radio features, granted you will have to torrent stuff you’re not necessarily familiar with first. If you have a few friends who also share their music libraries with you it can really help by including their tracks in your radios.
Settings > playback > radio > include external media
“Consider tracks from shared servers and TiDAL”
Also if you just mean multiple libraries like switching between them, click at the top. I’ve got 4 of my own and 1 from a friend here.