> Sometimes I'll get a pull request with like 2 lines of change and 120 lines of some reformating tool.

The reformatting tools should be CI-enforced so you'll only end up with sudden massive changes like this once when you start using auto-formatters.

Regardless, tell your teammates to separate out formatting changes vs logic changes into separate commits (preferably separate PRs). Since they're auto-formatters it wouldn't even be any additional work, just:

  git fetch origin
  git checkout origin/main
  git checkout -b formatting
  ./run_the_autoformatter.bash
  git commit -a -m "Ran the auto-formatter, which should have been enforced by the CI."
  git push -u origin formatting