After battery drain (or any other reason for a reboot...) and starting the phone back up you need to enter the passcode before being able to use FaceID. Would this mean that you can't use your phone if you drain the battery on vacation until you get back home?
Ensure you thoroughly read this article; it contains the answers to your questions regarding Stolen Device Protection for iPhones. About Stolen Device Protection for iPhone - Apple Support (IN)
Face ID or Passcodes remain active even when the battery is depleted and the device shuts down. Additionally, the Stolen Device Protection does not disable automatically in such instances.
The article simply says; "If you try to turn off Stolen Device Protection when you’re not in a familiar location, a security delay will start before you can turn it off."
What happens if you drain your battery during vacation with Stolen Device Protection turned on?
