l recently saw a study that said coffee can stunt breast growth. Is there anything else that can do this, or anything that can elevate their growth?

Plastic Surgery.

weight lifting makes them perkier[x

Your breasts mainly compose of fatty tissue anything that breaks down fatty tissue can make them smaller but the only thing that will make them bigger is more fat but the rest of you gets bigger as well so not a good idea

No breast growth is down to genetics and your personal distribution of body fat and of hormones .Nothing alters them significantly apart from pregnancy.

try gaining weight, then loose the weight and your boobs will still be big.