Have the United States of America, instead of having a democratic system, have a Monarch have power. As and added condition the Monarch must have some power over the country.
Not going to happen, not with a PoD after the US wins the ARW. The Founding Fathers were desperately afraid of tyranny, and limited the size of the Army, for instance, to keep the Federal Government from getting too strong. In fact, the original constitution was the Articles of Confederation, which gave the Federal Government almost no power. There was LOTS of discussion over the Constitution, but the only reason the Presidency has as much power as it does, is that Washington was going to be the first President and everyone trusted him to set the right precedents.
Could 'King' have been the title of a LESS powerful presidency? Yes. But that would involve a MORE democratic government, not a less one.