I understand that royal babies are given several names, and they choose one of them when they become king or queen. I don’t know if this was always the case, but the Queen’s dad Albert, became George VI. So this may be a newish thing, about 100 years old.
Prince Charles, who as Prince of Wales and second in line, has four names. Charles Philip Arthur George.
People assume incorrectly, if he should become king, he will be King Charles III. That’s not the case. He’s publicly stated he would take the name King George VII.
King Charles the first was beheaded by Oliver Cromwell, which I think leaves a bad taste for future Charles’. And Charles the Second was very popular with his people, but I still think it must have been horrible to grow up knowing daddy had his head chopped off.
(Personally I think he should go with Arthur, that would be very, very cool)

I also think he wants to be George to honor his grandfather.