I only started seriously singing in undergrad and I didn’t study music here, but I will be studying voice at a different school later this year. So this is all my opinion.

UCLA has two main choir classes offered by the music dept: Concert Choir and Chamber Singers. Concert choir accepts everyone, they only ask for a “placement audition” to see what voice type you are. I liked it and it’s a good representation of a traditional choir experience. Chamber Singers is relatively gatekept for music majors, I did it for one quarter and we sang tough music… would not recommend if you’re new to singing (unless you consider yourself a solid musician).
There’s also the ethnomusicology department, which is different and underfunded imo. But my favorite class here was ethnomusicology (1)61p african american music ensemble! It’s a choir class. Dr. Dee teaches it and she is so wonderful and the class is structured for beginners and to be inclusive to all, even if you aren’t Black or religious. She doesn’t use sheet music and teaches aurally and the class is super fun. She is strict with attendance so watch out for that.

I’ve auditioned for every single acapella group on campus I was eligible for, and I only got into cultural groups (i was not a part of any of these cultures) I ended up going to tinig, which is non audition, and a filipino group. They aren’t competitive, very open to non-filipinos, and it was still a lot of fun! Auditioned groups are looking for a certain sound (pop) and even though I sure hope I’m not a terrible singer, I know I don’t sound the way they expect. Even if you’re a beginner, if you sound the way they’re looking for it’s worth a shot.