Does nylon and/ or spandex shrink?

I have this bikini I just bought from a thrift store, I still have the tag on it. So I only got the bottom because I could just wear a white tank bathing shirt on top. I was contemplating on returning it because it's too big, but if I could wash and dry it and it shrinks. I would go back to get the top also so if it were to shrink, it would fit. It is made of 82 % nylon and 18% spandex. Thanks ahead of time!