As highmarking noted above, California is huge, much bigger than the UK, and with a large population. Northern California is a very different culture, and climate, to Southern California. In addition to the Latino & Asian population there is a large white working class population in all the cities (of course, as everywhere), Bakersfield for example having an economy based on oil and farming. Farming is huge in Southern California.
When people say Harry won’t like California they are thinking of the upper middle class to stinking rich minority and their in touch with their feelings ways. Well, loads of British show biz people love it there, so maybe he will hate it, maybe he won’t, but being British does not preclude enjoying it. I’d hate the heat and the smog & wouldn’t want to live in America, but if you like the heat LA has a lot to offer (amazing food scene for one thing, even for average incomes).
I would think if he’s disatisified it might be due to missing friends and being deferred to and being bored to death.