Currently Elisa already does synchronized lyrics that are embedded into the Lyrics id3 tag. Apparently the same formatting used for synchronized lyrics in the Lyrics id3 tag is used for LRC files: https://en.wikipedia.org/wiki/LRC_(file_format), so if you copy the contents of an LRC file and put it into the song metadata with Kid3 it shows up in Elisa. Usually, when a music player supports LRC files, you just need to have an LRC file in the same folder as the song. It would be nice if Elisa supported this. If you want to test this with an LRC file, you can use Android's LRC Editor on a certain song or I can supply one.
A possibly relevant merge request was started @ https://invent.kde.org/multimedia/elisa/-/merge_requests/464