I need to factory reset my daughters iphone. She forgot her passcode and we cannot get into it.

If your iPhone has iOS 15.2 or later installed, see: How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support

If that option is not available, you will need to use a computer. See: If you forgot your iPhone passcode - Apple Support

Try to put it into recovery mode and then set it up again. Try following directions on this article:

If you can't update or restore your iPhone or iPod touch - Apple Support

Hope this helped

How to reset your iPhone, iPad, or iPod touch when you forgot your passcode - Apple Support

Try to put it into recovery mode

Not possible if you have forgotten the passcode.