I can't upgrade my MacBook mid 14 to big Sur because i am unable to log into my Apple ID since it doesn't support it.
I'm unable to upgrade to big Sur since my MacBook doesn't support me loging in to my Apple ID. The model is MacBook Pro mid 14
You can create a new Apple ID and use it. As far as the old one, just forget about it and use the new one.
If your Mac doesn't support you upgrading to Big Sur, changing your Apple ID will do nothing. The ability to upgrade to a given OS is based on year and model Mac, not your Apple ID.
Of course if your Apple ID is not accessible, that's a different situation.