Can I bolt a plate to the floor and use leveling pins or jacks between plates?

You can certainly do that, but it’s simpler to just use leveling feet on the table legs and tack them to the plate on the ground.

If you use two plates, you’ll still have to tack the feet to the top plate so the table doesn’t shift off. There is really no need to do that since the leveling feet can still adjust height when welded to the plate.