Will Otoplasty Help Headphones Stay in the Ears Better?

Most earphone "buds" are placed within the cavum conchae of the ear. In many patients undergoing otoplasty, the cavum is reduced. This potentially could have the opposite effect you desire of making the earphones more difficult to place and retain.

Generally speaking, an otoplasty should not meaningfully affect the fit of ear buds. The exception to this is in cases where the antitragus (the little cartilage protrusion above above the earlobe) is very laterally curled. This anatomy occurs in a minority of patients, but otoplasty can make such an antitragus appear more prominent, thus requiring a reduction of the antitragus as well. But the antitragus is one of the edges that can help hold ear buds in place.
So, although uncommon, an otoplasty could make ear buds fit worse. That said, I've reduced the antitragus when needed and I've not had a patient mention a poor fit to their headphones afterwords (yet...).
All the best,
--DCP