How to Sing on a Slow Down Track and a Newly Recorded Vocal

I'm going to be getting into a technique That's pretty old school, it's really like slowing down a track Singing on the slow down track, speeding the track and a newly recorded vocal Back to the original speed and you have a high pitch vocal in key Which is different to taking a vocal, singing on the track at the regular speed and then pitch shifting it obviously. It just allows you to, as a performer, get a lot more nuances out because you've got a lot more time to do all of your runs  and I found an app online that would let me type in ratios of tempo. Nowadays I'm recording primarily in Ableton and I really kind of don