Right oh, some more engineering 101, to counter the harm of dewdman's fake news.
Proximity effect. You really should have googled that one, dewdman. It refers to a property of most microphones whereby very close sources tend to elicit an enhanced response at lower frequencies, compared to the mic's frequency response to the same source at much greater distances. It could perhaps be more properly called the "close proximity" effect, since it becomes noticeable within about a metre or so between source and mic.
I'm willing to be wrong but I very much doubt if any of VSL's sample recordings have ever deliberately invoked the proximity effect. Otherwise mixing with VSL sample libraries would include the ever-present chore of EQing out the proximity effect on instruments that are to be placed farther back than right in your face!
The "Proximity" plugin that I assume you found in your random googling (as if Paolo can't google for himself) has a facility for EQing in or out the actual proximity effect of a typical microphone, but this of course has nothing to do with making a distinction between 10 metres and 15 metres, for example.
And you say this is the same as the other EQ-distance effect that I carefully questioned; i.e. the HF absorption of air (now you can google ISO 9631-1), which plays very little if any significant part in distinguishing differences between player positions on stage.
Tut tut. A big bit of noob confusion there by you, methinks. And yet you still make it sound as if you know what you're talking about, and that can cause untold mischief and confusion amongst non-technical music makers who all too often just accept what they're told to do about the technical stuff. They need to be protected from fake news merchants out just to make a name for themselves by any means, fair or foul.