The viewport meta tag is set. The layout viewport width will be set at device width.

Body element (red border; no width set, implicit width of about 100% of layout view width) + div element (blue boder; 2000px width).

On a phone with about 400px visual viewport width (e.g. Pixel 2), the layout width is also set at about 400px. There is no scaling.

The page body (red) will occupy the whole screen (about 400/400) and the div (blue) will be shown wider than the screen (2000>400), about 5 times (2000/400) wide.

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