Print as mockup
All designers print or export their designs with a stroke that defines the paper size. That stroke could be replaced by a fill that simulate a certain paper colour (prefs defined) and a short subtile dropshadow.
It would be great to have in the print/export dialogbox a function that could do that for you, simulate a certain paper colour for the background and a dropshadow. Print as Mockup function
It is possible to re-define "paper" color in InDesign to be any cmyk or probably rgb color. I am not sure how that would transfer to a pdf or other export format.