No. Sports betting is not legal in California, but that could change as soon as November 2020.
Multiple bills have been introduced the last few years, but nothing was close to happening until 2020 when tribes started mustering support. As long as they get enough signatures, a sports betting initiative will be on the November 2020 ballot, though the Coronavirus pandemic delayed the process.
Even if the initiative passes on the ballot, regulations will still have to be made, which means sports betting likely wouldn't launch until late 2021. Unfortunately for some, the bill would only allow retail sportsbooks at casinos and racetracks, not through online operators. According to survey numbers, the majority of California voters don't want mobile wagering.
Horse racing betting is legal in person and online, while Daily Fantasy Sports are allowed without legislation. There have been numerous attempts to pass a law legalizing fantasy sports, but California's gambling powers haven't been able to agree on regulations. Until that happens, unregulated DFS contests will continue in the state because they're considered games of skill.