Once you build them, they are yours to use as you wish.
It’s a good idea to learn how to store them on gihub anyway. And then you can create a github page and use it as a portfolio. Or you can host them on your own site?
Can you link to them directly, where they are? Well, where are they? If they are in codepen, you could in theory link to them there, but it looks a little amateurish to use codepen as a portfolio site.