LEANDRA MEDINE, a fashion blogger who lives with her parents on the Upper East Side, was thumbing through the hangers in her bedroom closet on a recent Monday morning, pulling out the sort of items that she calls “sartorial contraceptives”: a blouse with erect shoulder pads from Zara; a floral, curtainlike blazer by Zimmermann; high-waisted lime green trousers by Opening Ceremony; drop-crotch utility pants; an ostrich-feather miniskirt; a cape.