Need to jack up a porch about six inches

Two story porch too? Can you describe the size and what's on top? Also what's below ground, if you know? Can you see concrete at ground level or slightly below, if you move some grass?
Jacking up a big enough porch can be risky, so I'll let the building trade people answer, but please describe in more detail.
Also, does it really need 6" or is some of that slope by design, for runoff?

That is a lot to lift. Footing dropped? There must be some separation with a 6" drop. One end or across the whole porch?

Joy and Brian both touched on some of the points we need so we can help you.

Size of porch/deck.

Location of support posts and girders.

Are footings below the frost line?

If possible, a picture would help.

Chuck