Yes, it is possible to transfer from an a OOS college to the UC’s however, OOS transfers have low priority for admission. The hierarchy for UC transfers is as follows: California CC > UC to UC > Cal state to UC> CA private to UC > OOS to UC.
The main issue is articulating OOS courses to the UC transfer requirements. Transfers in California can use the following website to help plan their transfer courses: assist.org. What you would have to do is look on assist.org to find the required transfer courses and then try to match them to the OOS university courses.
Also, why not apply directly to the UC’s as a Freshman unless costs are a limiting factor? As a transfer, you will still have to pay OOS fees for at least 2 years at the UC’s so that still is around $120K.