Would a sliding genioplasty help make my face more masculine and bring more facial harmony?

Thanks for your inquiry and providing a photo. The short answer is yes. Some jawline definition would help too. I prefer to tackle both with an implant. They are relatively simple to place, have a short recovery and provide great aesthetic results. Best of luck. 

A siding geniplasty is an isolated chin procedure whose aesthetic benefit can be determined by computer imaging for you to determine whether that is beneficial. As an alternative you may be better served by chin and jaw angle implants or a custom total jawline implant. 

Yes. You have a mild microgenia and sliding genioplasty would be a beneficial procedure to you 

You have to consider the 'front/mirror' view as well, since your growth pattern appears to have a 'narrow' lower jaw; so that a genioplasty may need to be combined with jawline augmentation to achieve your goal

 Hi, I have performed many facial shaping procedures using dermal fillers, slastic facial implants (cheek implants, chin implants), liposuction and/or facelifts for over 30 years.  Following my beauty principles, men look chiseled and handsome with angularity in the cheeks, chin and mandibular angles.  From the photos, your cheeks are flat in the front, the chin is weak as are the mandibular angles.    The following procedures would create a more ruggedly handsome face.
Cheek augmentation with silastic cheek implants to add angularity to the cheeks and mid face.  Liposuction can be combined to reduce any excess fat to further shape the cheeks and face.  If you are not ready for implants, Dermal fillers can also be used.
Chin augmentation, using a chin implant, to add projection to the chin creating harmony and balance to the lower face.  I have performed many facial shaping procedures, including Chin Augmentation with dermal fillers or silastic chin implants, for over 30 years.  When the chin is weak, this creates an imbalance making the nose appear larger, the mid face top heavy, the lower face looks short, de-emphasizes the lips and allows early formation of a "double chin".  Proper placement of a silastic chin implant adds forward projection to the chin thereby creating harmony and balance to the lower face.  Using the same incision, liposuction can be performed to reduce the fat and further shape the neck.  Excess skin, from below the chin, can also be removed through the same incision.  I have found that placement of a silastic chin implant, through a small curved incision under the chin (also allows excess skin removal) to be very safe, quick, highly effective and far less invasive than a sliding genioplasty (requires extensive tissue dissection, bone cuts and placement of metal screws and plates to secure the cut bone segments).  I perform chin implant surgery in 30 minutes or less, often using a local anesthetic alone.  In my opinion, you are a good candidate for chin implant surgery.  
Augmentation of the mandibular angles using a dermal filler (jaw implants have too many unwanted side effects IMHO) to add volume, angularity and flare to the jaw line.Hope this help.