From the product page:
Also are included HD Concave and Convex morphs for Genesis 3 Female for realistic denting in a skin.
So the developer of that outfit created matching morphs to create that as a special effect. It's not something generically available.
You could possibly create a similar effect by applying a D-former with a "less than 100% scale" but you'd have to apply it to the figure itself, not to the clothing, since the clothing follows the underlying figure, as opposed to vice versa.