Expanding the lung’s capacity is not accomplished by forcing more and more air into the lung. Nor is the personal control of one’s lung or anything else about the lung accomplished by filling it up more and more with air.
The attempt to increase lung capacity by filling the lung more and more with air is an enormous misapplication of logic. The way lung capacity is and can be expanded is not by forcing more and more air into it.
Singers, athletes and others trying to develop lung capacity and control may well, by accident, actually increase their lung’s capacity. But that is the inadvertent result of something else they are doing, and they do not have a clue what that is. And their attempts are far less efficient and rational than doing it right, with correct understanding of how the lung works, in the first place.