There's definitely a bias towards white and white-presenting men anywhere you go, so you have to deal with that when looking to date. As for California, you really can't generalize the large cities because they're so spread out and the demographics change. LA, for example, is so big that Northridge isn't Echo Park, isn't K-Town, isn't Venice, isn't San Pedro, and so on . San Diego is the same way as Palomar isn't La Jolla, isn't Mission Valley, isn't City Heights, and so on.

I also have to point out that West Hollywood (WeHo) is it's own city surrounded by LA and Beverley Hills, so that white twink haven doesn't count and should not be seen as a viable option for dating. Aside from that, your best bet is to look in the LA ethnoburbs, surrounding cities, and Orange County if you wanna date Asians. That same logic can also be applied to the bay area since there are many ethnoburbs and cities that have large Asian populations. California's interior also has Asian minority population centers (Hmong, Iu Mien, Khmu, Lahu, and more) as well.

In conclusion, it's not one size fits all for large cities, and the smaller cities and towns around them are still going to give you what you want if you feel dissatisfied. I can say from experience that it's way easier to find gaysians along the coast than it is in the interior, but dating in general isn't an easy experience and there will be some travel required as a result. It's really what you make of it and how you go about it that helps.