If you’re referring to the control center that you open by swiping down the top right side of the screen….you face would unlock the device when you wake it unless it was just powered on and the code was needed the first time or the other situations that would require you to manually input password before Face ID would work….or the phone was already unlocked (like you were already actively using the phone. In that instance there would be no reason for the control center to be locked. If you are wanting this because you unlocked the device and are letting someone else use it that you don’t want to be able to access anything in the control center then you can choose to set up restrictions via parental controls for the items eligible that you may have in control center. Or you can toggle off access within apps. Or you can remove items from control center you are worried about someone accessing.