Torsion axles can come with the arm in several different positions, the arm up, the arm straight, the arm dropped, I presume you have drop arms on your trailer. Most of the arms are fixed in this position, but a few manufacturers make axles where the arms are adjustable on the axle.
If you have adjustable arms then you may be able to reset them to get more drop.
Gaining six more inches of lift out of the torsion axle through adjustment would be almost impossible unless the arms are currently in an upward position.
When there is a difference in height between the trailer and the vehicle it is usually accounted for by using draw bars with different drops and raises, are you just trying to adjust for the height difference or do you want the trailer to have more ground clearance?