How to update a mid-2012 MBP (13”, i7, 16gb RAM, 1tb SSD) that already has OS Monterrey from an old version of OCLP? Also thoughts on running Sonoma on 2015 MBP (13”, i7) and 2017 5K iMac (27”, i7)?

I used OCLP to install Monterrey on a 2012 MacBook Pro (13”, i7, 16gb RAM, 1tb SSD) about four years ago. I also have a 2015 MBP with the same specs, and a 2017 5K Retina iMac (27”, 40gb RAM, 1tb SSD) that are both on Monterrey too.

I am thinking of bringing all three Macs up to Sonoma specifically so I can use a more recent version of Final Cut Pro (11.1+) and related plugins (and possibly also to use Resolve). I know that the ‘AI’ functions won’t work, but lots of other more recent functions will.

1) How do I update my 2012 MBP that already has an old version of OCLP on it from late 2021? Do I need to remove or replace that old version of OCLP before I can install Sonoma?

2) How well does Sonoma run on these three machines, specifically for FCP? I edit projects from an external SSD, and use the Macs just for Mail, web browsing, Pages, Numbers, Keynote, and some Photoshop (and I might start using Resolve).

Thanks!