Body element (red border; no width set) + div element (blue boder; 2000px width).

The viewport meta tag is NOT set. The layout viewport width will be set at 2000px (as 2000 > 980).

On a phone with about 400px visual viewport width (e.g. Pixel 2), the scale factor of 0.25 will be applied (normally it should be 400/2000=0.2; but 0.25 is the lowest limit). so the layout viewport width will be actually about 1600 not 2000 (400/0.25). The page looks smaller.

The page body (red) will occupy about 5/8 of the the whole screen (about 980/1600) and the div (blue) will occupy a bit wider than the whole screen (2000/1600=1.25 times).

Compare this with 5-2000px-meta.html on a mobile device.