There is one thing that I feel like Joshua can do to exploit a flaw in Wilder's style.
AJ doesn't really move his head like that, but he keeps a high guard on defense and he does bend his knees to duck punches every now and then when he's facing opponents his size. He has a naturally composed fighting stance.
He'll need to keep that in mind once he gets hurt and Wilder starts getting wild and flailing bombs to finish him. Most dudes try to back up and create distance, but fail since Wilder already has a crazy reach so dudes end up getting caught at the end of his punches. The guys who don't back up, make the mistake of bending forward like Ortiz, but they end up getting caught with rabbit punches and they can't see the punches coming.
Joshua needs to duck/crouch (not bend over forward) while maintaining his high guard and stay close to Wilder. He'll make Wilder miss with those wild hooks, but it'll also make Wilder throw the uppercut. Joshua needs to parry/deflect the uppercut and counter that with an overhand right. Wilder is open for that punch. These heavyweights need to train to react to Wilder during this moment, because it always happens and nobody knows how to get through it.
The opposite of everyone having a plan until they get hit