Will a sliding genioplasty narrow the chin?

Only a multidimensional ossous reduction genioplasty may narrow horizontally, make rounder and less "heavy" the chin.Additinally this procedure may provide the vertical and anterior increas you seek.Beware! never ever accept chin implants or fillers, they lead to
complications, unhappy patients, poor results and actually don't
provide what your chin evidently needs: augmentation in 3 spatial axes.
Seek the help of a surgeon with experience in multidimensional
genioplasties (beware, you are NOT a case for a basic and simple sliding
genioplasty).
If you wish better grounded opinion well lit,
focused and standard images have to be assessed: frontal, both lateral
and both oblique views, also underneath the nostrils.

Feel free to request any additional information from me.

Without an exam your question cannot be answered.  You will need to see an Oral/Maxillofacial surgeon to see if othognathic surgery, genioplasty or using an implant is best for your specific case. It should be noted that patients with severely weak jaws or abnormally functioning jaws may be better treated with other facial surgery (orthognathic surgery), although a chin augmentation may be an option at a later time. These patients should seek the advice of a plastic surgeon to determine which course is right for them. Here is some information to help you make this decision: Candidates for Chin Augmentation - Patients whose chin profiles are weak but have normally functioning jaws are candidates for Chin Augmentation. Many of these candidates have used injectable fillers in the past to strengthen the protrusion of their chins, but are looking for a permanent solution. If you are one of these patients, then you are a likely candidate for chin augmentation
#weakchin #chinimplant

A sliding osteotomy is not designed to narrow the chin. The chin can be narrowed by shaving down the sides of the chin through a small incision under the chin or inside the mouth.. 

Sliding genioplasty is an extreme surgery that I don’t recommend unless you have functional issues. To fix the cosmetic problem of a weak chin or projection, a chin implant would give you the correction you want. You must find an expert facial plastic surgeon to help you with this. I hope this helps.

Depending upon the amount of horizontal movement a sliding genioplasty will either keep the chin width the same or may slightly narrow it. In more uncommon cases the chin can be widened as the bone is moved forward by a midline split and grafting.