Classically, Congress held the power of the purse, able to both bar and require spending. This imposed a significant limit on Presidential power. With a bought court supporting him, Trump would have significant ability to essentially chart power as a king.
The point of our system of government is to test different methods of government and see what worked best. That’s why states have more powers than the federal government.
Turns out the red states consistently wind up much worse than the blue states.