With the birth of Prince Harry and Meghan Markle's daughter, Lilibet Diana, come new questions about royal titles. Both Harry and Meghan still use their titles as Duke and Duchess of Sussex. Even though they've hinted at dropping the name. While at one point they even wanted to license the title as a brand to make money off of it.
At this point, that situation is all a bit of a mess because of the split between the Sussexes and The Royal Family. However, there are laws the dictate when their children could get titles!