pretty much what the title says. i like using a gui but would settle for a good cli version
yt-dlp (a fork with more features), both in Fedora repos.
$ yt-dlp -x --audio-format=mp3 https://youtu.be/tkOXilZNbRU
You could add a shell alias to make it more convenient to use.
More examples here: command line - How to download an MP3 track from a YouTube video - Ask Ubuntu
If you are looking for a gui youtube downloader app video
flatpak install flathub org.nickvision.tubeconverter
For audio app
flatpak install flathub io.gitlab.zehkira.Monophony
I second the Monophony proposal. Great app.