Being a royal, especially when in line for the throne, you get a certain title. That is how Prince William and Kate Middleton’s daughter, Princess Charlotte got her title, a princess. But being the eldest daughter that is not the only title she might get.
In the past, male royals had the privilege over female royals in the line for the throne, even if they were born first. Thus the eldest daughters were assigned with a title Princess Royal. This royal title is transferred to the next royal princess in the line for the throne.
Current Princess Royal, Princess Anne, is the eldest daughter of Queen Elizabeth II. After she passes away, her royal title will be transferred to Princess Charlotte, the eldest daughter in the line for the throne.
But it doesn’t mean that upon the death of Princess Anne, Princess Charlotte gets the title automatically. Sometimes we can wait for years for a princess to get her new title. According to Duncan Larcombe, royal expert and author of Prince Harry: The Inside Story, “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.”
It’s all up to her parents Prince William and Kate Middleton when will their daughter be presented with a new title. It is most likely that she won’t be entitled with this name before she gets married because, according to British Royal tradition, anyone who gets intimate with Princess Royal before marriage, will be sentenced to death.