Kate Middleon can completely change her appearance, but nothing can absolve her of royal etiquette. In fact, the protocol specifies that Middleton must bow to anyone directly succeeding to the British throne, which she does not have to (via Marie Claire). This includes her children: Prince George, Princess Charlotte and Prince Louis of Cambridge. However, if Prince William, Duke of Cambridge, is with her, she won’t have to bow as she will be cornered in his place in the line of succession.
Follow BBC, the British line of succession currently sees Prince Charles succeeding his mother, Queen Elizabeth II, and after him Prince William. However, three points directly behind William are his three children in order of their birth. Only after William and his three children did the successor go to Prince Harry. Because they’re lining up directly for the throne, Middleton has to bow to them, though we doubt she actually does.
Furthermore, Marie Claire explains that royal etiquette is often relaxed outside of official royal engagements, meaning a lot of bowing is reserved for these occasions. However, people usually bow to the queen. However, the line of royal succession and its interesting rules are still extremely attractive. For instance, did you know that Meghan Markle has to bow to Middleton?
https://www.thelist.com/671630/why-royal-protocol-dictates-kate-middleton-bow-to-her-kids/ Why does the Royal Protocol forbid Kate Middleton from bowing to her children