@medigull Why are you so set against staying in high school if you don’t get in after applying your junior year?
In my opinion, there is no clear reason stated that would make CC a better option. Unless there are very good reasons to not be in high school your senior year I completely agree with @10s4life (Reasons to not stay in high school could be: you are already attending your dream college, you are in a private high school that costs a lot, you have personality conflicts with other high school students, teachers or administrators, your high school has overly restrictive policies on whether you can take classes outside of it, there is literally nothing more to take at high school, or …)
If your high school does not offer enough rigor, you should be able to take CC classes next year and the following year to supplement high school. Then, you can apply junior year (and you’ll have a decent shot with a good SAT score). Then, if junior year does not fan out, apply again senior year with stronger stats. And then, if you don’t have enough to get in on the second try in your senior year, you should have enough to apply from a CC as a transfer the following year.
IMHO, likely the same as others on this thread, your best chance at UCLA is in your senior year of high school. I know admission rates are higher for California CC students who transfer, but there is more self-selection with respect to who applies. My guess is that it is actually tougher to transfer than get in as a freshman.