You cannot do it on Indian models because of Government regulations, which requires phones to have an emergency mode mapped to triple press of power button. However, if you use Always on display, you can set double tap on home to open camera.
Thanks for part of Samsung community. Would like to tell you sir would like to tell you the power key is predefined for particular action and it can not be made as shortcut of camera.
U can do it only if u keep the Always on display enabled. once u enable the always on display and go to always on display settings u will find the quick launch camera option
