In 1942's Larceny Inc., Jack Carson, a really big guy, wears a big polo coat with the confidence of man comfortable in his clothes. He also shows how, contrary to today's thinking, some clothes look right fitting in a "big" way. I tried, but couldn't find a full body shot, but these pics should give you some idea of how he looks in it.
For fans of '40s style, the movie is full of suits, ties, overcoats, hats, etc. from the era. And since it stars Edward G. Robinson, despite being only an okay story, he makes it worth seeing.