Can u tell if a patient has had chest surgery in the past just from the chest x-ray?

May/not. When you post on this site the more details you provide the more likely we can provide a reasoned answer. Simple procedures on the chest wall may not trigger any changes that would show on an x-ray. Inserting a breast implant likely would. Surgery inside the chest that involves the lungs may leave scarring or metallic clips that would be visible.

In general major surgeries will remain visible due to anatomy changes and typical hardware used, minor procedures will not leave changes that will be perceivable with an X-ray.