Does screen replacement on iPhone require erasing all data on phone?

If you need to have your screen replaced, you need to make sure the phone is backed up as Apple cannot guarantee your data won't need to be erased in the process of replacing your screen.

You should always have a backup. If you wait until you think you might need one, it could be too late. If you set up your phone to use iCloud to back up, it will perform the backup every night. That's best practice.

Or that something goes wrong and the entire device needs to be replaced.