The growth of chest and other body hair is regulated by hormones in the body and, as such, it is difficult to predict whether chemical treatments, such as testosterone will increase such growth. Unless affected by disease or illness, hair growth is determined by genetics.
Various chemical treatments, such as testosterone, have been used to increase hair growth. However, there is no guarantee that such treatments will affect the chest specifically.
Body hair is affected by hormones. The production of testosterone in male testes and female ovaries during puberty in particular aids in the development of chemicals that lead to the growth of body hair and the percentage of such growth is dependent on genetics. Despite myths, such as the notion that cutting the hair to increase growth, there is no guaranteed method for increasing the development of body hair.