Replacing the battery on an iPhone SE

A. Is it possible to get a new battery for an iPhone SE?

B. How much would it cost?

Trying to determine if my elderly father-in-law needs to get a new phone. He’s perfectly happy with his SE but he was told his battery could die any day now, so he’s afraid he needs a new phone.

I don’t think he needs a new phone, as long as ge can get the battery on his current SE replaced should it be required.

please advise