So far I´m informed no. Especially the costrophenic angles do not directly correlate with lung volume (the supposed reason for your question?). Experienced radiographers often prolongue their fields down to the iliac rest not to miss the lower especially posterior part.

Observation- Fat patient's lungs occupy very small area of the film whereas the thin and tall patients demonstrate a full of length in a film usually.

Also might be a problem associated with a volume of air inspired by these two category of patients.

It´s very plausible, but I don´t know any quantitative algorithm.

The prologing of fields is no real dose problem, because modern thorac radiographs belong besides the teeth pictures to the real low dose expositions.