Wiki:I don't know of any adult 18-a-side competitions that didn't adopt the 50m penalty.
Some (particularly amateur) leagues and competitions use a 25-metre penalty. Examples of this include the South Australian National Football League (SANFL), Victorian Amateur Football Association (VAFA), Australian Football International Cup and the Australian Amateur Football Council.
Point is, its not dictated by the AFL.That is a law change made by the SANFL. It was taken up in part by the AFLW.
A lot of overseas leagues have modified boundary laws.