Charles doesn't require to have a coronation in order to be king, since he was crowned king shortly after the death of his mother.
Prince George and Prince William are currently the first and second line for the throne.
As a sovereign, Charles has also assumed the titles of his mother, defense of the faith as well as the head for the Church of England.
He is also in charge of the Commonwealth the title of which is not inherited, but is chosen by Commonwealth officials.
Queen Elizabeth has previously stated that she had a "sincere wish" for Charles to assume the title.
The motion was officially ratified by the leaders in April of 2018 following the late monarch's approval.