No It doesn't:
I have a 2.5 inch Rough Country spacer, and bigger tires (33's) and didn't void the warranty. I had axles seals replaced and 5y100k covered it. So no spacers will not void warranty. If a lift is done correctly void warranty (to an extent), if i were to have installed 4-inch and 35-37's I would have to have the dealer install different gears and reprogram the tranny. If i had a IRF do the re-gearing then yes i would have voided the warranty, It must be done at a FCA approved dealer and your golden.
Prior to installing lift i called 3 different dealer ships Fremont, Walnut Creek, and Stoneridge, because initially i wanted to roll on 35 with a 4 inch. They all said i would have to re-gear or void warranty if i were to install a tire that was 315 70 17 or larger. I have 3.55 gears, 3.92 or 4.10 may be different story
Im talking about 5y100k, factory bumper to bumper is said to be the same....
3rd party warranty, yes may void warranty.