Yes - two options.
You can add soft armor level IIIA cummerbund inserts. These are sold in a set of two. See link below.
https://www.opticsplanet.com/shellback-tactical-level-iiia-model-clciiia-soft-armor-package.html
To add 6 x 6 hard armor side plates, we will need to purchase side plate pouches. These are sold in a set of two and attach to the inner side of the cummerbund. That way the plates sit between the cummerbund and your body. See link below.
https://www.opticsplanet.com/shellback-tactical-side-armor-plate-pockets-2-0.html
This armor package comes with 10" x 12" ballistic plates which is designed to protect your vitals (heart and lungs). The shoulder straps are adjustable which allows you to raise or lower where the plates fit on your torso. The cummerbund is adjustable which allows you to loosen or tighten the fit around your torso. This armor kit works best on individuals who wear tshirt sizes between medium and 2xl.
These plates are model 4SICMH. They are 10" x 12" multicurve level IV plates that weigh only 5.7lbs each.