Some people will never admit that certain politicians have charisma if they do not politically align with them - stupid but true I often vote Labour, although I have voted for all 3 of the main parties in England, and I don't think Blair had charisma, he always seemed a bit creepy to me. I don't think Johnson has any charisma, I find him cringey, can hardly bear to listen to him. I am grown up enough to accept that other people have their own opinions.
I think the last British politician I really thought had charisma was Paddy Ashdown, I think they've gone down hill since then. Can't think of one that I'd say has charisma now regardless of the party.
It is so funny that people can't accept you actually have an opinion and have to make up their own reasons for what you say.
If you look at America I am old enough to remember Kennedy as having charisma, although I always preferred his brother Bobby. Obama has charisma in my opinion.
I think charisma is a bit like sex appeal, I don't mean you have to fancy a politician I mean one man's meat is another man's poison. There isn't a science to charisma, it is subjective Boris Johnson has more hair than Dominic Raab, fact, Boris Johnson is more charismatic than Keir Starmer - like beauty it is in the eye of the beholder.