This isn't going in the power levels subforum because this isn't a traditional powerscaling post.
Her battle with Kaido is Yamato's main fight in this arc. Not just in this arc, it's the main fight of Yamato's life. Yamato is fighting for her freedom, for the right to forge her own path, the right to choose her future. This is a battle for self-determination:
Yamato will never again wage a battle with such
deeply personal stakes. No matter what happens from here on out, never again will Yamato be fighting for her very soul. She'll never again fight for the right to assert her own existence as an independent person.
If you think the most important fight of their life for a character as important to the plot as Yamato is going to end with Yamato getting stomped, then you're not only reading the wrong manga, you're reading the wrong genre.
One Piece is a feel good Shounen. When such battles are waged, it never ends with the character getting stomped. Yamato will lose eventually, but Oda is not going to draw Yamato getting no/low diffed against Kaido when she's fighting for the most noble motive of all.
Like what message do you think Oda will be trying to send by that?
Yamato vs Kaido is Wano's equivalent of Law vs Doflamingo.
Just as Law lived the last 13 years to strike down Kaido:
Yamato has longed to be free of Kaido for at least the last 20 years:
Ace told her not to let Kaido chain her heart:
And now, 4 years later she's come to break that chain:
Before you start jerking off to your headcanon powerscaling, actually understand the narrative at play here. Understand what this fight means for Yamato's character. Understand the genre you're reading.
Just as Doffy reserved the position of "Corazon" for Law (and not Pica or Vergo):
It is Yamato (and not King) that Kaido seeks to make Shogun:
Yamato vs Kaido is Wano's equivalent of Doflamingo vs Law. Claiming that King is stronger than Yamato is about as sensible narratively as claiming that Pica was stronger than Doflamingo.
Because Law's main fight of the arc was vs Doflamingo, he had no business being weaker than Doffy's strongest subordinate.
Because Yamato's main fight of the arc is vs Kaido, she has no business being weaker than Kaido's strongest subordinate.