This is apparently an upcoming feature in iOS12 but doesn't work in iOS11 now
What does work is putting the wrong finger on your sensor until it tells you TouchID is disabled and needs your passcode (which is 5 times) or rebooting your device without logging in.
What does work is putting the wrong finger on your sensor until it tells you TouchID is disabled and needs your passcode (which is 5 times) or rebooting your device without logging in.