Before growth plates have closed, mk677 or HGH will make you grow taller. These effects can be exaggerated by:
-IGF-1 DES
-Reducing oestrogen with an aromatase inhibitor and increasing testosterone production by using hCG. This will effectively delay the closure of the growth plates during puberty. What the consequences of that are, no one really knows yet. Could also make your dick bigger by increasing the reduction of testosterone to DHT relative to oestrogen aromatisation.
Post growth plate closure, there is little that can be done. I have read about people experimenting with Relaxin to relax the ligaments holding the bones together, but this is pretty esoteric stuff.