This is going to bug me... I was reading A book from the 80s/90s with a stage magician and a couple women and it reminded me of a trilogy of books I read in the late 1990s as discarded paperbacks from my local college (the bookstore would "destroy" remainder inventory by cutting the covers off to indicate that they could not be resold and then giving them away). I could have sworn that the trilogy was titled something like The Magicians, but of course, it's hard to find anything with a title like that due to the popularity of Lev Grossman's books. The protagonist is a wealthy middle-aged white man, maybe British, who witnesses what he believes to be true magic, and the trilogy follows his initiation into the rites, which as I recall it, always keep just to one side of it being a scam and/or a matter of personal improvement rather than actual magic. I remember that he had to travel to various places in the world in search of the esoteric wisdom he was seeking, and that at one point, maybe in the third book, he winds up trapped in a cave, and has to get out via a narrow passage, resulting in a scene where he exits the small hole naked and covered in a mix of mud, blood, and his own fecal matter (having lost bowel control during a time when he thought he was stuck) with the book either explicitly stating the parallel to childbirth, or it just being very heavily implied. I honestly don't remember if the magic turned out to be real or not.
Since the books were part of a college bookstore's inventory, they might have been recent books that were meant to be part of a literary analysis class. They were all fairly thick paperbacks, larger than the typical pocket paperback, but smaller than a coffee table book, in my memory at least 300+ pages each. What I could see of the cover artwork looked colorful, although as noted, much of it had been removed to "destroy" the book. I have a vague memory of the titles being named after mythological creates like gryphons, sphinxes, or basilisks.