I had one about 6" tall. just regular bag-seed so I don't know what it was. It grew in a 6" pot and went straight into flower.
yea my friend has a few small ones she just picked the 6 incher theres like 2 that are 8 9 inches and they just have one lil bud going on the top wish i had a pic for you
all autoflowering ones grow fast, and very short. the ones i grew were only about 16" tall. maybe 18 i cant remember. they had more then just a little cola and u can top them too
Heres a 10-12 inch purple thunder I just harvested. It was a clone that got bad heat stress while in a 1 gallon black pot for a month and never recovered, instead it went into protection mode and actually made some resinous weed, i got 3.5grams
You have other options besides autoflowers and genetically shorter plants. You can start your grow later in the season to keep plants shorter. You can also limit the amount of roots by using less soil in your pot. This will keep the plant short but still allow it to give you a decent harvest. Growing on a balcony like me, I needed to keep the plant height short. So I planted in mid june and started the plants in minimal soil. As I was watching the plant grow, I added fresh soil a few times to encourage more rooting which gave the plant a small height boost each time, but I was able to control how tall it was getting overall. My plants are around 2 feet tall, and I should get a pretty decent yield off them when all is said and done. You could also LST the plant and top it throughout veg to keep heights to a minimum.