Can plastic surgeons make waist and hip bones smaller?

Fat: YES, Bones: NO: Body contouring is typically achieved using techniques to re-align or re-position, muscles and/or eliminate or reduce extra fat and lax skin. While boney contouring is performed in the face and extremites by craniofacial and orthopedic surgeons, respectively, pelvic bone reduction is not routinely performed for aesthetic purposes. I've heard rumors of rib contouring/resection but i don't know who.

Yes and no: It won't change the underlying bones but the fat overlying the hips and waist can be treated with liposuction.