It definitely does that for Youtube, but I didn’t see the option for Spotify. I last looked at the docs a very long time ago, so its entirely possible it’s got some added functionality since.

Just make sure to use a trusted one, because you’ll most likely have login with your account to access your saved stuff & playlists.

I used SpotDL, personally. Not sure if it even supports logging in, but you can just make your playlists public for a few minutes while you download them. It does require you to do every playlist individually, afaik, there’s not just a ‘my whole account’ option. If you have youtube premium/youtube music you can DL high quality as well, though getting that to work was a bit tricky for me. I don’t generally mess with programs lacking a GUI, though, so it’s probably mostly a me issue.