Could I enroll into different classes than my accepted major?

I’m going to be a first time freshman in SF State, accepted into the Civil Engineering Program, but I want to do nursing. My friend told me if I wanted to do nursing, when registration starts, you can choose nursing classes and your major doesn’t really matter. I don’t know if I should believe him, but he does have a sister attending there. How would that work out? Would my degree be in nursing in the end (when I graduate), even if I got accepted into another program?

Who else can I ask? I’m worried if I ask the school they might think im a liar or something.