It does 2FA. You have to implement emails yourself, but honestly it’s not that big of a deal (you likely have to do other emails for your app anyway).

It also does a bunch of other auth things, like OIDC.

Another reason to use Firebase is because they can provide a lot the advanced security (e.g. blacklists for 2FA phone numbers/emails coming from an algorthm whose innards are only known to Google).