For a demo on how you can accomplish a custom page, in Studio take a look at Pages > System > Home Page, in there you'll find a Splash Block with the code used for the default una landing page. That will give you an idea what is needed to make your own Custom pages. If you know css and html, it shouldn't be too hard to accomplish.

But there are many ways to make your own custom pages in UNA, it all depends on what exactly are the needs for your campaigns and how fancy you want them to be... https://una.io/page/view-discussion?id=7314