Yeah, even canopy is a key.
My last indoor grows were micro style, very little light penetration, so opened them up.
Why not a gentle LST, holding the base firm but pulling the top over 90 degrees to one side, then opening up the lowers in the other directions?
It won't slow down the growth at all, because not removing of the apical growth.
Then again, it's a Dutch Passion Lemon Kix? I have seen some of those get very big.
You say she's on day 18?
Has she shown any pistils yet?
Nowadays I try not to top autos after they show pistils and start the stretch. I think it interrupts them, not so good.