Punctures in the sidewall of a tire cannot be safely repaired so no you cannot plug the sidewall of a tire.
Tires have metal throughout the sides which are known as cords which make the repair of a sidewall impossible and even if it were possible a hole in the sidewall of the tire makes the tire dangerous because the cords could separate causing a tire blowout.
On holes in the tread area can be patched or plugged up but if a tire has a puncture or other damage to the sidewall then the tire is no longer safe and needs replaced with a new one.