Do T Shirts or Clothes Protects the Scars Enough from the Sun Exposure After Gynecomastia Surgery?

Thanks for the excellent question!  You are right to be concerned about sun protection and you should continue this concern for about a year post-op.  Regular garments will not provide the necessary sun protection.  I would recommend daily application of sunscreen for one year.

While healing the wound should be protected from the sun with sunsceens (SPF 50 and above).

Regular clothes and T shirts do not protect from sun rays (Ultraviolet, Infra red). There are specialty clothes that have and give protection from sun.

I would recommend avoiding the sun until your scars are mature. Scars are not mature as long as they are pink in color.  Protective clothing is a good choice, as well as applying waterproof sunscreen.

If you have the traditional incisions around the areola they must be protected from the sun for many months. For many years I have done the operation through a tiny incision inside the armpit which is completely invisible. This requires no sun protection.