say that the bigger the person the greater the possibility of stretching due to the simple fact that larger people have bigger tendons, it is a proportion ratio, small people have tendons and small muscles so stretching is proportionally smaller,
then in the arms there is no way to predict a safe elongation because it is not standard will depend on your current size and tendons, a doctor will analyze and can predict how much can be stretched and the probability that you can not stretch is great,
because the arm is much more sensitive than a leg you do not use the feet to write or eat so lose some sensitivity in the feet no problem already in the hands can harm you for the rest of life.
in the article that I read about stretching for corrections of deformities and dwarfism, I did have forearm stretching, but these patients already have the side effects of mobility problems so in case they have nothing to lose, but aesthetically it is very risky to lose a limb that works perfectly for pure cosmetics