There are some uses of NAA for increasing the longevity of flowers on flowering plants and causing shorter spacing between nodes. I've read a couple studies regarding its use.
I'm against using PGR's on cannabis for the purpose you want so I'm not going to provide any details on it's usage except as a rooting agent. You can find studies online. Follow that methodology if you really want to use that stuff on your cannabis.
You'll be better of just training your plants to stay low. You can scrog outside. Get a net and train the plant horizontal and don't let it grow vertical.