[empath-nirvana]

There's entire books and blog posts and youtube channels that go into all of this. Music production is all about creating a "space" and a lot of what producers do is create the illusions that sounds are coming from particular places, and that sound like they're from a "big" source or whatever.

A common thing to do is to pan a synth to one side, then add a very short (milliseconds) delay panned to the other side, which makes it sound like a very large sound played from a large distance away.

Another is stacking up a bunch of oscillators that are slightly detuned from each other, which again, makes the sound "big", because it sounds like many sources playing together, rather than one source.

Just using a "reverb" is generating an illusion of being in a large, echo-y space.

I do think that most producers don't really think of it as creating illusions, and more as making "cool" sounds.