You can top/fim them when young. The thing to remember with autos is from the minute the bean pops they are on a death timer. In about 70ish days they are done ready to harvest. Left growing they just die. Topping might stunt so it's a risk.
You can break main cola dominance by training the plant and keeping the main cola tied (LST). That way you get a bunch of large buds not just two.