for genital care of boys we have to retract the excess skin till what age? my child is 3 years old and the head is not vastly revealed. should I do something about it or it will be fine on its own?

That is fine. A gentle wash with water is suffecient. Please check out useful articles written by our Mom Champion

Allowing your child to take a tub bath or soak for a few minutes in water can help clean this area really well. Retract till point of comfort but don't force.

till what age should it be done?