No, that is not a plug-in model, there is no electric-only mode. It is just a motor-enhanced ICE.
This is old tech (like the old Prius), and doubtful to be the future. The future of ICE in HD towing is likely a Series Hybrid, like a train locomotive. An ICE driving a generator that runs the electric motors. This is both more efficient as well as being more robust (gets rid of the transmission weak link). It is rumored to be what Ram is working on.