Shoulder width can't be reduced, but you are only 16 years old and your figure is still developing. You shouldn't be so strange when you are fully grown up. When I was a child, my neighbor told me that my shoulders would be very wide in the future, and I am really big now. As long as you grow taller, the shoulder width will not be so prominent, so pay attention to your height and strive to grow. Massage your chest more and eat more nutritious things. Remember not to hunch over or shrink your chest. It's not so good for the development of bones, muscles and meridians, and it's not good for your future manners. You should be thin. Just eat yourself fatter and eat more evenly. Development and adolescence are always strange, and then it will be fine ~!