It turns out the inhabitants of anthro Equestria, despite being built like sex objects, get offended when you ogle them like sex objects. Go figure. A human that lands in Ponyville quickly becomes a pariah and is nearly run out of town, but a timely yet suspect intervention from Discord turns things around.
Imagine if you could do or say anything you wanted and no one would mind. Imagine if you could tell people what to do and they would come up with a reason to do it. That's the kind of power this human obtains. Except it's not quite that simple.
Now his main obstacles are his out-of-shape body, his lack of self-confidence, his morality, and the sneaking suspicion that the magic inside him is just waiting for the right moment to turn him into the most normal stallion in the world instead.
Indulgence ensues.
If you recognize the concept of "universal acceptance" or "normality" from mind control fiction circles, this may be for you because this is basically that.
Warnings: Mind control, moral pondering, proportions ranging from hyper to merely big, a wide variety of partners, the exploration of many fetishes relating to size, happy endings, and sex.