Aug 11 2021 10:32 AM
Hi there, you are welcome to the Microsoft Edge Insider Community Hub!
This feature is there in the Microsoft Edge PDF viewer I guess since it was released to the public.
What you need to do is click the button depicted below which toggles into two different modes when you click, one is fit to width and another one is fit to page. Fit to page is the option that will show the whole page in the PDF viewer.