Please be aware that phalloplasty offers no guarantees. It is possible for the penis to retract post-surgery and for the situation to be worse than it originally was. Infection is another possibility. On the other hand, it also possible to gain 1-2 inches in length, and a little more than that in girth. It depends purely on your unique situation and the quality of the surgeon.
That’s for augmentation phalloplasty. In the case of FTM (female to male) transsexuals, it’s possible to take skin from the forearm and fashion something resembling a penis. Forearm skin is used because the underside is generally hairless in most men. This is an entirely different procedure, having nothing to do with penis enlargement surgery.