In iOS14 Apple added a new feature to “Autoplay Similar Tracks” when a playlist or queue is finished. Its supposed to continue to play similar music to what was on the playlist. Similar to Create a Station that does work (but is fairly buried in Sonos and Apple), but instead it kicks in at the end of an existing playlist vs. creating an unending playlist from scratch like Create Station does from a selected song.
Apple show an infinity symbol on the player to control this feature.
Its supposed to be somewhat better than create a station as it has the context of the entire preceeding playlist when picking a new song, vs. a single song.