Princess Charlotte is set to inherit a new title when Prince William is crowned King.
William will be the King of England, Kate will become Queen and Prince George will be next in line to the throne. And while Charlotte will remain a princess, she will inherit another title: Princess Royal.
However the title at present belongs to Charlotte’s great aunt and the Queen’s sister, Princess Anne.

“The title of Princess Royal is traditionally bestowed on the eldest daughter of the monarch,” Royal expert Duncan Larcombe told Town and Country.
“Princess Anne had to wait until 1987 before her mother the queen bestowed the title of Princess Royal on her, even though the title had been vacant since 1965.”