Following Saturday's coronation of King Charles III, he automatically became custodian of immense power which he will wield all through his reign.
For starters, he became the supreme governor of the established Church of England.
It is also his mandate to approve all legislation, summon or dismiss Parliament and act as the commander in chief of the British armed forces.
But more importantly, the King's other main function as head of state is to appoint the Prime Minister.