re: "I want to ask whether is it possible to add work history if you have previous experience outside Upwork?"
It is not possible to manually add anything to your "Upwork job history."
You may add employement history.
You may refer to prior experiences in your free-form overview text.
You may post examples of past work in your portfolio.
Dear brother, you can share your experience which you had outside of Upwork in the "Employment History" or in the "Other Experiences" section on your profile but you can not put it in the Upwork history that is not possible. I hope it helps you to understand the basic rules of Upwork.
Have a good night..!!!