Orange County, Ca used to be one of the more RC friendly areas in the country. That is not the case any more as the county and cities have prohibited RC flight in most public gathering areas. Flying from school yards is now just as bad, if not worse. In general, the area governments forced most all RC operations to distant outlying areas.
Best bet is researching local flying clubs through the AMA website and speaking with them about approved areas.
Orange County has had lows on the books prohibiting flying RC aircraft of any type in County Parks for a very long time. They mostly ignored them until the advent of prolific numbers of drone pilots in the parks. Then they clamped down.
Having said that, there are still places to fly. You need to stay out of the John Wayne airspace and they are not real friendly about drone flying, even Part 107 pilots.
Keep in mind that the area is densely populated and it can be a challenge to find a safe place to fly where you are not over flying people, busy roads, etc.
I see people flying drones in the Dana Point Harbor area on occasion, and along some of the beaches, etc.
Do some online research to see what the laws are in a city you are interested in flying in before flying. Remember, the FAA owns the airspace, but a local government can control what you do while standing in their city, etc.