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.
Being president when a plague happens isn’t awful. Being president and responding to a plague like a Nurgle cultist, however, is.
If everyone would have just injected bleach then no one would have died from COVID.