UCs do consider first generation status in holistic admission reading.
CSUs generally consider only (recalculated) GPA and SAT or ACT (superscore) to calculate an eligibility index for; applicants are then ranked by this eligibility index for admission to the campus or specific majors, with preferences for state residents and local area residents in most cases (some campuses and majors are open to all applicants who meet baseline CSU eligibility). CPSLO uses its own formula (see https://mca.netlify.com/ ); it considers whether parents graduated from high school.
https://lao.ca.gov/Publications/Report/3724 has some information (not admissions) on first generation students at California public colleges and universities. Note the differences in definition of “first generation”. The community colleges define “first generation” as no parent or guardian has ever attended college (42-55% of community college students, depending on data source), while CSU and UC define “first generation” as neither parent has a bachelor’s degree (54% of CSU new frosh and 46% of California resident UC undergraduates).