personal UX project.. edits, changes, mock ups.. is that it?

Total newbie to UX design here.. like TOTAL noob (as you’ll see from the upcoming question) I’m currently wrapping up a class on UX core and fundamentals and, naturally, am wanting to start up my portfolio with ‘personal projects.’ I already anticipate a resounding DUH from anyone who’d be so gracious to take the time to respond to my post, but I just wanted to make sure: personal projects are purely hypothetical, right? I take a product or website, mock it up, dismantle and reconstruct it into a better, more intuitive version with fantastic UI, info architect, pleasing-to-the-eyes aesthetic, etc.. as well as document what, how, and why behind every tweak... but besides having it reviewed by acquaintances in the field for feedback, I don’t actually submit it, do I? Any personal project would simply be a “this is what I would do to improve this website/product” scenario/exercise in itself, am I right?