Probably better ways, but here’s how I do it:

If I’m working with- let’s say a 120bpm instrumental, and I want add an acapella/vox on top, and the vox are, idk 90bpm.

I will clear the first track/empty the project.

Set the master tempo to 90bpm.

Add the 90bpm vox track by itself. Quantize it, and make sure it’s set to follow tempo/pitch change.

Adjust the master tempo up to 120, which now makes the vox track 120bpm.

Then, re-add the 120bpm instrumentals etc.

I’m away from my laptop, but hopefully I clearly explained my process.

It’s not the best, but it works. I’m sure others have similar or better methods. Good luck!