That is not how it works. Luffy did no damage in this chapter. Luffy in any form can't take attacks more than base Kaidou can take.
thats not how it works
shanks cant take more attacks than base kaido either
he isnt durable
but he can fight equally with hybrid kaido
if this continues
its fair to assume he's above base kaido. you dont powerscale based off the attacks one can take
thats just simply endurance/durability
luffy prob evades or blocks most of the attacks kaido was eating like he was braindead.
and btw he did damage kaido last chap.