"Well, you know what you're getting because he's been practicing for a bit, and I don't think he'll change," she told CBC News in an interview that aired May 1. "He's committed to his own level of service that will remain true."
So how is the royal family preparing for this next chapter?
"We've been very lucky," Anne said. "My mother was the queen for a very long time. And although you kind of know that this might happen, you don't really think about it very much—not least of all because the monarchy is about continuity. But I think for my brother, you know this is something he's been waiting for, and he's probably spent more time thinking about it. For the rest of us, it's more a question of, OK, we have to shift the way we support, and that's what we need to do."
As for how Anne will be supporting Charles on his coronation day, she'll be fulfilling an important job.
"I have a role as Colonel of the Blues and Royals in the Household Cavalry regiment as Gold-Stick," she explained to the news organization. "Gold-Stick was the original close protection officer. So that is a role that I was asked if I'd like to do for this coronation. So, I said yes. Not least of all, it solves my dress problem."
King Charles III's coronation will be the first for the British royal family in 70 years. The last was for Queen Elizabeth II in 1953, which then-Prince Charles attended at the age of 4. Princess Anne, who was just 2 years old at the time, was not there.
"The whole service will be different in many respects," the royal, now 72, shared. "He was just old enough to have gone to my mother's coronation. I don't know what his impressions were. I was not allowed to go, probably quite rightly at that stage of my career. It could've been way more trouble than it was worth."
And while Anne says Charles' coronation will be "such a different scenario," its significance remains.
"There is so much in that service which you really have to do that is fundamentally important," she later noted. "It is the meaning of the coronation in every way. It's not just a big ceremony. It is a very essential part of the responsibilities of the Crown."