Yes, the free songs on YouTube aren't customizable: there's a low voice guide that you can't turn off (or turn up...), and you can't change tempo.

You can do this from their huge catalog of songs, using their official app or their web client: https://www.karafun.com/web/

Plus, they have music quizzes you can play with many people using smartphones as remote controls. It's super fun for parties where people don't want to sing all the time.