When you input your password, then your biometrics (faceID, fingerprint, etc) become active. A restart requires you to enter that again. The police can make you put your finger on your phone or look at it, but they can’t make you divulge your password without a court order.
There are have also been some exploits that are possible ONLY while the machine is booted and already in that state unlocked state, rebooting relocks all the HW encryption and clears main memory.
When you input your password, then your biometrics (faceID, fingerprint, etc) become active. A restart requires you to enter that again. The police can make you put your finger on your phone or look at it, but they can’t make you divulge your password without a court order.
There are have also been some exploits that are possible ONLY while the machine is booted and already in that state unlocked state, rebooting relocks all the HW encryption and clears main memory.