Install a door on an UNLEVEL subfloor

So you're renovating your house and the floor isn't level, what's the best way to install a new door to keep the frame square?
Tools used: (or better ones) FYI Affiliate links - no extra cost for you
6ft Level: https://amzn.to/3iF3ebF
Rotary Laser Level: https://amzn.to/37I0ST2

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