If you are in lake elsinore, you are probably going to carlsbad?
Carlsbad is not doing loaner cars right now (or wasnt roughly 10 days ago when I was there last). You can do a "touchless" drop off by getting out of your car, and texting your advisor (respond to the text they send you pre appointment with the information). If you prefer to talk to them in person, they have it setup so that you can go inside the building and they have dots on the floor to indicate where to stand, and they have their mobile kiosks setup like 10-12 feet away from those dots with temporary posts indicating where to stand.
If you are going to go into the building and talk to them, you need to have a mask on, and they are also wearing masks. As I mentioned, no rental cars at all, but they are offering uber credits (like I actually wanted to get into an uber, lmao). If you have something short being done, you can wait in their waiting room, with your mask on. When I was there, I was there about 1.5 hours or so, and only a couple people were waiting in there and we were very spread out. When I needed to take a phone call, I went outside, and there were also a few people milling about outside, definitely more than 6 feet apart though.
As far as cleaning the car, etc, I am not sure. I picked up my car, drove home, got home and washed my hands, and went and wiped down my steering wheel, thats about it for what I did.
I suggest you have someone follow you there and pick you up, unless you are comfortable getting into an uber (I wont be getting into a rideshare vehicle myself for the forseable future). My thinking on rideshare vehicles is, anyone who is driving those right now is doing it "for a living", its not a "side gig" and anyone like that is not going to stop driving because they have "a few sniffles". So, no rideshare vehicles for me. YMMV of course.