An S-400 missile battery has more range than the land attack weapons they are supposed to use the F-16s for. Including the cruise missiles. Even Buk-M3 has 70 km range which is more than any of the PGMs in use by the US.
As an air to air platform the old F-16 being provided to Ukraine is utterly outclassed by the Russian Su-35 or MiG-31BM. It uses a planar array radar with upgraded electronics, and the Russian aircraft use upgraded PESA radars with much higher area and power. Those Russian radars have similar performance specs to the AESA radars in the latest versions of the F-16 of which there are limited numbers in service.
Plus, like I said before, the Russian aircraft can use the R-37M missile which has twice the range of the AIM-120C AMRAAM.
As an air to air platform the old F-16 being provided to Ukraine is utterly outclassed by the Russian Su-35 or MiG-31BM. It uses a planar array radar with upgraded electronics, and the Russian aircraft use upgraded PESA radars with much higher area and power. Those Russian radars have similar performance specs to the AESA radars in the latest versions of the F-16 of which there are limited numbers in service.
Plus, like I said before, the Russian aircraft can use the R-37M missile which has twice the range of the AIM-120C AMRAAM.