I purchased a brand new sealed iPhone but later realized the battery health is showing service, is that possible?

Assuming you purchased an iPhone X (as indicated below your post) at best you purchased a device that has been sitting on a shelf for years. That model was discontinued 4 years ago. Lithium Ion batteries do not take well to being left discharged for long periods of time. The battery is probably toast.

What model is the phone and where did you purchase it from?