You can temporarily disable Face ID by long pressing the side and volume up buttons, or by pressing the side button five times quickly. Either way it brings up the off-switch screen, and Face/Touch ID won't work again until the phone is unlocked by passcode.
I understand the thought behind turning all this stuff off, but I think knowing you can quickly and temporarily disable it if you're in a situation where you need to is good enough. I say that from a place of privilege, of course, but I figured it might be of interest to people who don't know.