Although Duke and duchess are not higher titles than Prince
Charles's title is HRH Prince Charles, The Prince Of Wales, Duke of Cornwell
Camilla's is HRH Camilla, Duchess of Cornwell
Camilla's official title mirrors her husbands exactly. Charles is His Royal Highness The Prince Charles Philip Arthur George, Prince of Wales, Duke of Cornwall, Earl of Chester, Duke of Rothesay, Earl of Carrick, Baron of Renfrew
Camilla is HRH The Princess Charles, Princess of Wales, Duchess of Cornwall, Countess of Chester etc etc.
She is just styled as HRH The Duchess of Cornwall. Just as in Scotland she and Charles are styled as TRH The Duke and Duchess of Rothesay
William's is HRH Prince William of Wales, Duke of Cambridge
Catherine's is HRH Princess William, Catherine the Duchess of Cambridge
Catherine's name doesn't feature in her title. She's just HRH Princess William, Duchess of Cambridge. Her own name won't feature in her title until she is Queen consort, or she gets divorced.
Harry's is HRH Prince Henry (Harry) Of Wales, Duke of Sussex
Meghans is Meghan, Duchess of Sussex
Meghan is HRH Prince Henry, Duchess of Sussex. Same as Catherine.
George and Louis are prince name of wales
Charlotte is princess charlotte or wales
The Cambridge children use HRH Prince/ss X of Cambridge. William and Harry were Wales because their father was POW. Legally they have no surname so George is simply HRH Prince George. They just 'need' a surname occasionally so use their father's Dukedom.
Archie could have been Earl of Dumbarton or Lord Archie Windsor and then HRH Prince Archie of Sussex when Charles becomes King.
However, the use of Mountbatten-Windsor suggests they've chosen no title at all because that is the surname for the descendents of the Queen and Prince Philip who carry no title. Even though Louise's birth used Mountbatten-Windsor surname when she is being referred to by title she is Lady Louise Windsor. It looks like they've decided on no title for him either now or in the future with the M-W choice