This ruling doesn’t get into that question. Based on how courts treat refusing to take a breathalyzer, I’m guessing it opens you up to being detained for 24 hours on suspicion of a crime, giving them time to obtain a warrant. A different write-up says that if you do not give a password, they can detain your device and make you wait; but you are not required to give up the password. No other write-ups I can find mention the password issue.

I know previous rulings have said that Face Unlock does NOT count as forcing your password and is allowed by police in searches. When I go on international trips, I disable Face Unlock on my work phone before going to the airports to block that pathway since my phone contains company proprietary information and Controlled Unclassified Information (CUI). I have nothing embarrassing or illegal or incriminating on my personal phone, so I usually don’t bother.