Yes, it does support 4k Videos shooting as well playback.
Yes, it does support OTG.
Yes, You will get Moto Style mod free in the box.
Yes, Moto Z2 Play does have OTG support.
Standard packaging includes Mobile Phone with in-built battery, FREE Style Mod, USB Type C Cable, USB Power Adapter, SIM Ejector Tool, User Manual and a pair of Headphone.