That appears to be the bed width between the wheel wells. I assume it would fit width wise on top of the wheels, which is still in the bed. As to the length, not even most full size trucks are long enough to fit the whole sheet. I guess the main point is that you wouldn't have any trouble getting the sheet of plywood home.

In my old Ranger there were a couple of spots in the bed where you could put a couple of 2x8 beams across it and have a place to stack 4x8 sheets. You did have to lower the tailgate, but they didn't stick out past the end of the lowered tailgate so there was no special requirements (flags etc...) for hauling them. It was very convenient. I would hope this truck has a similar feature, since it's almost free to add and increases the utility greatly.

8 foot beds do exist. They're very rare nowadays with nearly every truck being a super-extra-mega cab 4 door.