Yes, you can. GVWR is calculated by the manufacturer in stock form based on the stock components ... frame, axles,tires, length, etc. Most of the things people do to their vehicles wont change how much load can be safely carried. But to stretch the logic so its obvious if you replaced a vehicle frame with one that was fully boxed, stretched it, went from half ton to one ton axles, installed heavier springs, heavier steering and drive components, changed to load range E tires, etc, and did it all correctly the functional GVWR would definitely be higher. No calculating by how much but definitely higher.