No, the UC’s do not Superscore. You send all test scores and they will consider the highest score from a single sitting.
See the UC Website:
Report ACT and/or SAT scores on your admissions application, then request that an official copy of the scores be sent to us from the testing agency. You can have your official score report sent to one UC campus, and all campuses you apply to will receive it.
In the College Board’s Score Choice module, ensure that all scores are sent to UC. We require all scores and will use the highest scores from a single administration.
For the ACT with Writing test, we will focus on the highest combined score from the same test administration.
For the SAT with Essay, we will focus on the highest total score from a single test date.