Will Adjusting Torsion Bars Affect Alignment?

Yes it most certainly does. I did the torsion bars on my truck. I made sure to mark the bolts and cranked each side exactly even with each other to keep it as "equal" as possible. My alignment wasn't off at all which I found surprising.

Do you need an alignment after cranking torsion bars?

Yeah, the cranking will require an alignment. If the bumper shows significant sag then it may be contributing too to an alignment. It's not an immediate need but something you should not let go too long without addressing. Give the truck time to settle with the addition of the bumper and the new crank.

What happens when you tighten your torsion bars?

Adjust the torsion bar. Turning the adjustment bolt clockwise will tighten it, raising the amount of load that can be placed on the bar. This will raise the vehicle when it is taken off the jack stand. Turning it counterclockwise will lower the available spring rate and cause the car to sit lower.