This advice from Gruber is circulating again, and, it is good, but there is an important caveat:
Before interacting with authorities, hard lock your phone, sure. But in other situations using a biometric is MORE SECURE. Specifically: if you’re being surveilled, like if you’re in an airport, or near a cop with a body cam, unlocking with your passcode can leak it, which is game over. Do *not* start permanently disabling biometrics out of paranoia. Context is important.
https://daringfireball.net/2022/06/require_a_passcode_to_unlock_your_iphone