Hi jdr37
I am not with Laminar Research; just a flight simmer.
X-plane 11 is more resource hungry than X-Plane 10 requiring good graphics (GPU) and processor (CPU) speed to give you best benefit.
Have a look at the following link regarding system requirements found at https://www.x-plane.com/kb/x-plane-11-system-requirements/ Many serious flight simmers have a system that exceeds the Recommended Requirements ie Intel i7 7700k or 8700K CPU overclocked in excess of 4.5 GHz and a NVidia GTX 1080 or GTX 1080ti GPU. and a minimum of 16Gb of RAM. A NVIdia card will give you a better performance.
Follow the recommendation of downloading the demo first to ascertain if X-plane will "run" to meet your satisfaction. One issue you should also be aware of is good cooling is required within the case as the CPU and GPU generate a lot of heat. If your current machine has none then you should consider adding cooling as well.
In answer to your question an upgraded GPU will be of benefit but needs to work in conjunction with your other components.
Hope this helps
Glenn