Best to post a photo - but this is an unusual place for botox and certainly an off licence application. Creases on the chest may be better treated by peels / laser or surgical excision. Once creases have developed and there are deeper lines botox is not really effective. Make sure to consult with a experienced PS.
Withouta picture it is difficult to say what might improve the wrinkles on your chest.I have injected Botox into the chest to improve wrinkling and my patients havebeen very happy. Ifit’s the underlying muscle that is causing the wrinkling then injecting Botoxwill relax the muscle and improve the wrinkling.Ifthe wrinkling is caused due to laxity and damage to the skin then perhaps aresurfacing treatment would be best.Consultwith a Board Certified Dermatologist to see what procedure is best for yourconcerns.