How much taller will plant get after 12/12

I am close to starting 12-12 light cycle. Obviously the branches will fill out with buds, but will it get much taller? The plant is a 60-40 sativa, in soil, with combo of hps & T8 floros.

I do not want it to over-grow the enclosure.

So, 10%, 20% ?

Any assistance would be much appreciated.

expect it to at least double in size, if not triple. The main stretch period is in the first 2-3 weeks of flower.

What's the exact strain?

Subcool's Vortex

Ahhh vortex. Both parents of it like to stretch, especially the apollo 13 momma. I'd plan on it doubling in size minimum, if not triple. I haven't ran vortex myself, but I have ran the apollo 13 and my grow, along with all the other testers of that strain, more then tripled in size. Also my buddy has ran space queen which is the other parent and that always tripled in size too.