I would like to have iTunes display the lyrics while playing and auto-scroll to synchronize with the audio. I am willing to add ID3 tags or XML or some other such thing to lyrics to support the sync, but I am not aware of a format/syntax to do so.
“Cover Version” will display the lyrics (and any embedded codes) but no auto-scroll (and it is unsupported since Yosemite and iTunes 12.6.1)
Get Lyrical and LessLyrics sound useful, but I would really like to do it in a visualizer in iTunes on both iPad and MacOS. And neither (nor "Get Lyrica") is in the app store.
As I was typing this, a couple of possible duplicates appeared in the "similar questions" list, but just as I was about to click one, both links disappeared!