Well Trump can say whatever he wants, whether he actually can do what he says is another matter. In this case for example, congestion pricing has simply continued as before because Trump doesn’t have power to change the laws of New York. When it comes to killing people, government employees are subject to the same rules as everyone else about unlawful killing, even if they were ordered by the president. Of course Trump can pardon his assassins for federal crimes, but states can still prosecute them and if nothing else the victims can still use deadly force to defend themselves without being guilty of a crime.
So legally speaking, Trump isn’t so much a king as just some fat, old, possibly mentally-challenged man who can’t be punished for things.
But in the technical sense, we’re all kings and can do whatever we want. We’ve just agreed as a society that if people do certain things we all unite to help put them in a cage or whatever.
How are they going to stop it? Republicans have been trying to stop elections since 2017, they’re not smart enough to figure out how. They couldn’t even figure out how to schedule a press conference about it at the four seasons.