The British monarch is intended to be a living, breathing, unifying symbol–a sort of human Union Jack. As anyone who has watched “The Crown” knows, even though it comes with plenty of perks, it is a difficult job, because to do it right, you have to give up your right to live and think outside a very small box. Some members of the family can’t tolerate the limitations of the box, and suffer for it. Others learn to accept the tradeoffs and are more successful.
Elizabeth was a success. I think it helped that she was young and inexperienced when she became queen; she had the ability to grow into, and to some extent define, the job, and she didn’t have a record that would offend anyone. Charles is in the exact opposite position. He knows the role perfectly well, but he also has a lengthy record that does not exactly inspire confidence.
My guess is that he will be OK. The UK is a very different place than it was in the early years of Elizabeth’s reign, so Charles’ propensity for running his mouth will probably be met with a tolerant shrug, not a glare of disapproval.