Vin decoders are not going to be accurate for a 2018 model 3. It will not have a LFP battery if that is the question, but they should be listing exactly what model it is (Standard Range (SR), Standard Range + (SR+) or Limited edition Mid range (LEMR). Those are the only “RWD 2018 model 3” vehicle options.

A 2018 will not have come standard with autopilot as that did not exist as a separate package at that time. It would have had (standard) either nothing, enhanced autopilot, or Full self driving as a software option. “what it had standard” from the factory is only really matters if you are buying directly from the original owner, though.