Webside to PDF

Adobe Express does not have a function to export a web page as a PDF. See the page below for a feature request for what you're asking. You can vote for it in the page.
https://adobeexpress.uservoice.com/forums/951181-adobe-express/suggestions/47158525-export-webpage-as-pdf

Within your browser, you can print the page to a PDF. This will simplify the formatting however. For example, if you have a background image, it will not show. There is a complexity in converting a webpage, which could be scrollable horizontally and vertically into a PDF with a set page size.