Expensive and dangerous
No, it is NOT possible to make the penis longer through surgery (unless they come up with a penis transplant). It's basically an illusion. Though surgery techniques may be improving, why bother when you can get a bigger penis for, at most, a few dollars?
The procedure to "lengthen" the penis is by cutting the suspensory ligament. This gives the appearance of a longer penis but does not actually increase its length. It also makes the penis more unstable during intercourse and in do course more susceptible to injury. This surgery leaves a permanent scar. And a lower angle of erection (provided the surgeon doesn't screw up, and you never have an erection again). And - surprise! - without weights* after surgery, a person's penis may become shorter than before, as the body repairs the butcher's damage.
The other method of enlargement is by injecting or grafting fat from elsewhere on the body it around the penis to create a fatter penis. This gives the appearance of a fat, wide penis but not longer. These procedures are not recommended and have very high complication rates.
*Question: if weights alone produce genuine lengthening, why would a greedy, selfish plastic surgeon ever recommend surgery? Especially if he's going to tell you to use weights afterwards? And especially since the weights do the job on their own?