To answer your original question about ECs, leadership and VOLUNTEERING worked for the kids at my school for similarly competitive schools.
But don’t just randomly volunteer and get leadership roles, find a certain area you’re passionate about and volunteer and gain leadership in that area (tutoring kids, animal rescue, environmental or social activism, etc). It both will be more fulfilling for you and will go a much longer way.
Ps, Berkeley and I’m pretty sure also UCLA aren’t matches for anyone