You're probably better off posting over on reddit in /r/legaladvice they've got a pretty good pool of properly qualified people who will point you in the right direction. This is highly likely to come down to details about what is in your contract or any agreements you made with your employer as well as the jurisdiction. Talking to a lawyer is going to cost you much less than getting screwed by Tesla, so highly recommend going to one for some advice. Outside of legal avenues, I would suggest to you that saying to your boss "I'm willing to locate, but I need flexibility to push that date from August back to January" is most likely going to work if they really do want you back in the office. It's not going to work if (as has been widely suggested) the back to office order is just a pretense for getting people to quit without paying severence.

The other thing to do obviously is talk to them about how it's industry standard for companies to provide financial help for relocation- that should also give you a good idea how serious they are.