Passcode Won't Work

My wife upgraded from an iPhone 8 to a 12. We used the automatic data transfer. Now she can't get into the new one because it won't accept her passcode. She tried enough times that the phone is now disabled. The only conclusion I can come up with is to erase it. She's scared she'll lose all her data. However, I think it is in iCloud.

When I tried to get into her iCloud account to verify that her data is there, the two-step verification sends a code to her iPhone. We can't get into it to get the code, so I can't set her iCloud account.

Yikes! Any thoughts or ideas?

Thanks!