No, it's not the case (also rip if you believe Kaido used his entire awakening for a single panel without a single mention lmfao). He looks exactly the same like his zoan mode, only difference is that his lower body is shaped similar to Snake Man re-directing the trajectory of his arms. Kaido still has the same large neck like before.
Again, his zoan form looks almost the same. Meanwhile Porunga and Megidramon have the same muscular but humanoid upper body which I mentioned above. I mean, the next panel you can see Dragon Kaido completely again:
But you do have a point, his torso looks more muscular but Kaido also looks smaller than he is normally. I don't think that's his awakening. Zoan awakening is supposed to be the ultimate form, not a regression of his Zoan body.
Edit: I think Kaido was still mid-transformation but used this mode to copy Snake Man's technique.