You can always let the team know so that they can apply the formatter on their PR branch.

In the smaller migrations I did I tried that, but some way or another a decent chunk of the people still managed to get stuck in merge/rebase conflicts. I would almost explicitly not recommend giving that advise to the teams.

My rough blueprint for introducing formatter or linter nowadys would be:

- Recorded knowledge share session around how to set up the tools for local use 1-2 weeks before the initial rollout, and outline how the process will take place

- On the day of the initial rollout send out a reminder + the recording again

- Do the initial PR

- Incrementally do the rest of the migration, and subscribe to the PRs that drag out the process

This is exactly the remedy to the PR issue. I've "lucked" into owning a Prettier formatting pass at two different places now, and did the same process at each - full pass on master, simple step-by-step process to follow to update any PR by running the format script.