Want a chin/jaw reduction for vertical height but afraid of it projecting my jaw forward. Will this happen? (photo)

Chin reduction can be done by a variety of techniques, either intraoral or submental approaches. Each chin reduction approach has its own advantage and disadvantages. When only needing a near pure vertical chin reduction, an intraoral wedge reduction approach can be used. The squareness of the chin edges can be shaved down during the same procedure. It is not true that a vertical chin reduction always makes the chin project further forward. It is important when reducing the chin vertically by wedge reduction that it is moved back slightly to avoid that perception. Chin reduction surgery is a rather unique and uncommon procedure that in the right hands can be done well, whether they are a plastic or maxillofacial surgeon.

Your perception is appropriate: but it can be properly changed with a genioplasty and some recontouring of the adjacent jawline near the chin surgery. Consult a maxillofacial surgeon who do many of these procedures.