I don’t understand the car situation in California - thinking of visiting

So my partner and I thinking about visiting California from Europe as we have 3 weeks off work. I have been searching and reading about places to visit a etc but honestly I’m confused with the car/driving situation. So as I understand even if you decide to spent 5 days in LA you have to move around with a car? It seems a bit too far catch as someone who has never left Europe and don’t have any friend that has visited California.

Any tips and advice are more than welcome :)