A small closet doesn't need more square footage, it needs to stop wasting the footage it has. Most closets waste the space above eye level and below the hanging rod, and this list is built around reclaiming both: double-hang rods, slim velvet hangers...
swapped every wire hanger for these in one afternoon and my closet looks like a hotel now. nothing slides off either
Amazon Basics Slim Velvet Non-Slip Suit Hanger
added this under our existing rod and basically doubled the closet without giving up an inch of floor space