git apply patch to the rescue (question)

Hi,
I have a question: I've seen cases where a PR is really bad in terms of merging master multiple times, with commits before, in between etc. The kind of PR you want and should rebase, but it's really hard because of these merges.
In this case you can generate a patch, and then apply it on a new branch, to get the exact copy of your old branch, but less messy.

Is there anything in this guide that talks about a similar method? Or should I add that in a new PR?