SMAPI used to support lyric display, although I never saw a music service that actually implemented it. However in the latest SMAPI docs there is no mention of it, so I am guessing the ability was removed from the ‘updated’ mobile app.

TL;DR: never.

Depending on what you are expecting to see lyrics on, TVONOS supports Lyric display - but you’ll need an Android TV / Firestick or Android Tablet

(Not sure if I am allowed to post links - but should be easy for you to find)