A Catholic, yes. but anyone else is not under the popes jurisdiction. Of course, any assertion to the contrary is invalid on the face of it, but the pope has no secular power to compel obedience. Even his power to compel Catholics is limited.
RE: A Catholic, yes.
What about those who were baptized catholic from infancy and then grew up to become reformed and evangelical ( see for instance Evangelist Luis Palau). Are they under the Vatican I anathema?
RE: pope has no secular power to compel obedience.
Again, let’s dispel with secular power, wars, troops, etc. Those are relics of ancient medieval times.
Does the Pope have real SPIRITUAL power to anathematize someone who believes in Jesus Christ but does not recognize that he is the Primate of the Christian church?