[globular-toast]

I ran formatters on a largish codebase over Christmas when all the PRs were done. You just have to pick your moment. If it's really hard then get everyone to agree on a date to do it and make it each developer's responsibility to either merge before or rebase after the change. It can be done.

[random3]

Some team in my old job use to have a term for this - "grabbing the virtual chicken". It was essentially a giant distributed lock :)