Edge browser (and Chrome and Firefox too), are using the Windows screen size and display ratio to render. I have Lenovo Yoga 2 Pro laptop with a screen resolution of 3200×1800. If I set display ratio to 100%, then browser displays website smaller (website is 1200px wide, for instance, and the rest to 3200 is empty). But, if I set the ratio to 200%, it looks OK.
This is similar to iOS Retina display, but on the desktop and in Windows. It all comes to Windows settings for display.
Current responsive website trends usually require proper Viewport set for the website, and this is the meta tag (for the page HEAD) that is most common for the responsive websites:
<meta name="viewport" content="width=device-width, initial-scale=1.0" />