King Charles is head of state IN NAME ONLY.
He can’t start a war, can’t impose tariffs, can’t pass a simple law to round up stray dogs. The royals are parasites on Brits.
Neither can the US Head of State.
In his role as Chief Executive the president was given power to impose tariffs by Congress. But he may not declare war and certainly can not pass (the word you were looking for here is declare by the way, not pass) a law to round up stray dogs.
Civics. You really should have learned that in ninth grade.
But you seem to know nothing about either the US or UK system.