The hosel design is what sets the shaft extension line, so if we use the same head (constant COG) the hosel is the only thing that determines toe hang... You are rotating the club face during your swing, so you are just swinging the putter. There is movement in a few planes and axis.
If the shaft extension line is closer to the hosel this means more toe hang because of the in increased moment arm and less toe hang the closer it get to the CoG. I can send you some material if you want to look into it more.