This app tracks your rhymes and syllables, let's you break your lyrics into measures, has a visual and audible metronome, and more. No other product exists like this.
https://play.google.com/store/apps/details?id=kmcilvai.perfectpoet
found it on reddit(https://www.reddit.com/r/YouShouldKnow/comments/7pz41f/ysk_a_new_app_exists_for_writing_lyrics_and_poems/)