[2021] Can’t change email?

I’m am trying to change my email because I’ve gotten a new phone with a new email and have to send my old phone back to the store for trade in credit, and when that happens I’ll lose access to my old email (the one connected to the account) And then if it’s not changed I’ll lose access to the account. And not be able to play, I’ve tried everything to change it. Any help would be greatly appreciated. Thanks.

This is my first wipe, and I’ve progressed a lot and I don’t want to not only have to pay for a new account but also start over.