Increasing penile length requires releasing the suspensory ligament and the wearing of penile weights after the surgery. Releasing the ligament partially frees the penis from its pubic bone attachments, dropping it to a lower position, which may increase penile length or give the illusion of length gain. I usually perform the operation through a several-inch transverse (sideways) incision in the pubic hair. Many surgeons advance skin onto the shaft of the penis with VY advancement flaps. A V-shaped triangle of pubic skin is moved (advanced) to the base to the penis and closed in a Y-shape. However, a large VY flap based at the junction of the penis and pubic skin is not recommended, because it often produces a deforming hair-bearing hump at the base of the penis. It also is associated with a high incidence of wound breakdown. The low transverse incision does not cause such deformities.
Ligament release alone may occasionally increase flaccid (soft) length a half an inch, but often no gain is achieved. Releasing the ligament frees more of the penis to be stretched. Weights are suspended from the penis several times daily for a period of months. Flaccid (soft) length is often increased, and erect length gain is also possible. Length increases of several inches are rare; these claims are usually based on misleading measurements taken from the apex of a V flap. ……. a one-inch gain is considered a success even with the use of weights.”
You can see that the author of that page is a surgeon who earns performing penile surgeries, so probably those words are all but pessimistic.