Acting like what's in the offer letter doesn't matter is disingenuous because companies have reputations to uphold, and unless there's extreme circumstances, will generally honor what's been written down or in a job offer. I'm pretty sure there are legal ramifications too if you just completely switch job duties for employees willy-nilly. Most companies have enough foresight that if they were to put "remote" into an offer letter, it will be enforced from the top-down. Big 4's are huge companies, so even if your local team/partner is trying to force a return to office, you should easily be able to appeal to HR, point to the language in your offer letter, and at a minimum be moved to a different team.