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

Not possible if you have forgotten the passcode.

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