That would be an extremely bad idea. In that scenario, imagine FaceID fails to recognize you, now you can't get into your device. Currently if FaceID fails, you have passcode as an alternative way into the device.
Although fingerprint AND face/iris scan would probably add more confidence, with passcode as a reserve option.
No. As far as I know, there is no such device on the market. You can disable Face ID, but can't force it in combination with passcode, for example. Android allows you basically the same approach: any of the currently enabled methods. It is awkward though that there is no option to have that sort of 2FA for mobile devices, where at least two methods would be required, or strictly specified ones.