Would suggest that high school students looking into UCs take a look at Freshman admission by discipline | University of California to get an idea of which campuses and majors are realistic. To recalculate HS GPA for UC purposes, a handy calculator can be found at GPA Calculator for the University of California – RogerHub (the linked UC web page uses the weighted-capped version). For college students looking to transfer to UCs, take a look at Transfers by major | University of California
For CSUs, whether a campus or major is impacted (i.e. competitive admission, rather than admission at the CSU baseline of 2.5 HS GPA for California residents) can be found at Access and Impaction at the CSU | CSU . Where the campus or major is impacted, individual campus web sites may or may not have more information. For example, SJSU shows prior year thresholds at Freshmen Impaction Results | Admissions , but some other CSUs like SDSU and CSULB show much less information. CSU recalculates HS GPA similar to the UC weighted-capped version, except that a semester college course counts as two courses with two grades.