Phone on security lock

If you forgot the passcode on your iPhone, or your iPhone is disabled or unavailable -

Click on the link for instructions on how to reset your passcode without a computer if you have iOS 15.2 or higher.

If you forgot your iPhone, iPad, or Apple Vision Pro passcode, reset your device without a computer - Apple Support

Click on the link for instructions on how to reset your passcode using a computer.

Use a computer to reset your iPhone and your passcode - Apple Support

If you do not know the passcode, there is no way into the phone without resetting and erasing it. Any data which does not exist in other places (such as backups or iCloud) will be lost.

Assuming that the phone was associated with your daughter's Apple Account and that Find My was enabled, she will need to provide her Apple Account credentials to be allowed to reset the phone.