I've never seen one. I believe the suspension, frame, body, and drivetrain are all tightly integrated on these SUVs. It's almost impossible to lift these things. The differential, a-arm mounts, engine, and body all get in the way when you try to lift these things. I don't think a body lift is available either.
If it was a 2wd, the CST 5" spindle kit for the Colorado/Canyon might have worked. Since it's a 4wd, I think you're probably limited to a 2" coil-over or coil-spacer lift in the front. This would basically level the front with the back. You might be able to fit slightly larger tires.
Unfortunately, there aren't a whole lot of suspension mods for the Trailblazer or Envoy. Look up "Daystar Suspension" or "Performance Accessories" and see if either company offers a 1-2" lift.
A forum community dedicated to GMC and Chevy full size owners and enthusiasts. Come join the discussion about Silverados, Sierras, and other full size trucks performance, modifications, suspension, lift kits, tires, maintenance, and more!