Police can already unlock your phone using your face/finger prints. Been that way since at least 2018. But... they can't force you to tell them what to use

https://www.forbes.com/sites/thomasbrewster/2021/11/29/fbi-n...

Note there's a way to quickly turn off biometrics on an iphone.

Press and hold side button + volume up (or down) button until you see a slide to power off screen.

You don't have to do anything - at that point biometrics have been disabled and only a pin will unlock the phone.