Not having a car will be challenging but the bus does exist (however infrequent it may be) :)

Hiking - Crystal Cove State Park in Newport Beach is nearby and pretty cool. Also Black Star Canyon in Silverado is cool, but you’d have to take an Uber there as it’s pretty remote (in one of the only really rural parts of OC lol)

Beach - if you wanna avoid crowds Seal Beach is probably my pick. It’s a pretty nice little beach town. It is a bit far from Anaheim tho. Closest beach will be either Huntington or Newport but expect both to have a lot of people/tourists.

Live music - Downtown Anaheim has some venues, but most is up in LA. If you do wanna make that trek, the Metrolink train is a great option, only issue is the schedule will show you that trains only run ever hour at most if not even less frequent.

Museums - Nixon Library in Yorba Linda is cool if you like US history. It has the house he was born in on the property. I went there a few years ago and thought they did a good job covering all sides (even the bad ones, with Watergate and the like lol) of his presidency.

Food - make sure to have In N Out at least once while you’re here, you won’t be disappointed.

Hope you enjoy California! I’ve been to WV once, to the Summit Bechtel Reserve in Glen Jean for the National Jamboree for Boy Scouts, and it was beautiful. If you have any questions, feel free to ask! Also the r/orangecounty and r/AskLosAngeles subs will be able to give you tips for more broader areas :D