If I were POTUS, I would study the constitution in greater depth. After all, my job would be to preserve, protect and defend the Constitution of the United States. I would learn the ins and outs of what the Constitution represents and the context in which it was created to truly understand what it is trying to protect in our country.
If I were POTUS, I would endeavor to act accordingly and judge my decisions and actions in line with the tenets and whether it meets the basic requirements of the Constitution of the US. Certainly I will not get it all right like a constitutional attorney who has deeply studied it, but I am a US citizen and as POTUS, I would be a major representative of the citizenry of this country and a major job holder of an important part of supporting the Constitution. As POTUS I would need to understand it reasonably well, and make sure that my actions as POTUS and as an individual are representative of the values presented in the Constitution.