What procedures can I do to my face to get rid of the square shape and saggy cheeks? (Photos)

Youth patients with square face and saggy cheeks could benefit from both buccal fat removal and cheekbone enhancement respectively. 
Buccal fat removal is the plastic surgery procedure that removes the chubby cheeks to achieve a more defined V shape facial look in patient candidates. The video below helps to understand who could be a candidate for buccal fat removal. I routinely perform buccal fat removal.
Saggy cheeks are young age ( 20s) usually suggest the cheek bones are not prominent. Therefore, they shall be enhanced either with soft tissue fillers or cheek implants to 1) decrease the sagginess of the lower face and 2) significantly improve the results of buccal fat removal. 
The video below helps to understand who could be a candidate for buccal fat removal. I routinely perform buccal fat removal under local anesthesia, without any sedation, as an outpatient in the office setting. Cheek fillers could be done at the same time of the procedure. 

Thanks for your question and Pictures
The buccal fat pad is a rounded mass of fat in the middle of your cheek. It’s located between facial muscles, in the hollow area beneath your cheekbone. The size of your buccal fat pads affects your face shape.
Everyone has buccal fat pads. However, the size of buccal fat pads can vary greatly.
If you have larger buccal fat pads, you might feel like your face is too round or full.
You can be a candidate for a Buccal Pad removal surgery.
Best of Luck