I have plexpass which let’s me use plexamp. Personally I think it is the best feature Plex has. Plexamp rocks. You can sync offline by making playlists and having them download to your phone. It will auto update as you add more. Or just download whole albums.
Although plexamp has an arbitrary 24 limit on downloaded playlists, due to any higher causing issues. However that can be avoided by having multiple smaller playlists.
If you have a Linux server, you can use the features called sonic adventure and sonic sage. Sonic adventure let’s you pick 2 or more random songs and Plex will build a playlist that organically transitions between those choices.
Sonic sage requires you to have an openai api key but basically allows you to provide a vague description of your mood or what you want to hear and it will build a playlist for it. For example “songs that feel like a nice summer day on an early July morning” is a prompt you can have.
I don’t particularly like everything Plex does, but Plexamp appears to be their passion project and it sure does show. It has all sorts of unnecessary but really cool features. Like writing songs, playlists, or albums to NFC cards.