Dose the 4 pron reliance 30-amp twist lock plug come with the generator power inlet box. Thank you.

Yes it does come with the 4-Prong Male Plug in the Inlet Box. However, you need to dis-assemble the box to Hard-wire the Box (and its Plug) to the Auxiliary Transfer Switch, and/or the 30 Amp Circuit-Breaker in the Main Electric Panel for the Generator. Be sure to have either an Interlock-Slide/Switch or an Auxiliary Transfer Switch in place before utilizing the Generator, so as to NOT Back-Feed into Utility Power!