ChordAI is an app that tries to figure out the guitar chords for songs found on YouTube. It also has a lyrics function, which can generate the lyrics from the song.

There is probably an app more specialized for karaoke, but this was the first one that sprang to my mind.

Spotify has the lyrics for many songs and it will highlight the lyrics that are being sung.

It’s not the same as karaoke but pretty close

There are lots of karaoke apps out there, usually not free though.

I used this app for a party (4 years ago). Worked well enough: https://play.google.com/store/apps/details?id=com.anhlt.karaokelite

Moises is an app that isn’t directly intended for making karaoke versions of songs, but you could use it for that purpose. It separates songs out into their parts (guitar, keys, vocals, drum, etc) using assistive AI. You get a few free songs but you have to pay a subscription for more than that.

There’s also StarMaker but you’re limited to the catalog they have and it’s definitely got some dark pattern design. Can be a bit fun but I deleted it pretty quickly.

Apple Music has pretty good karaoke for some of their songs. Not sure if there is a catalogue out there.