Oda literally has to keep upping Feats arc by arc while portraying equalization narratively for certain characters to keep tension. He’s a victim of his own power creep.
Crocodile alone proves this. We saw a VERY weak luffy beat someone that later stood on buisness to most of the top tiers at Marine ford. Certain characters are always just going to be as strong as they need to be.
Dorry & groggy are another example of this. Based on how they talked about them at little garden, the leaders of the giant pirates should be as strong as they were at egghead. Defending against the gorosei and stuff. But at the same time they lost to Mr. 3 when they first showed up.
Or like Rob Lucci is supposed to be this legendary assasin for the world government, but then lost to the first pirate that showed up haki-less.
I think its more likely that characters are scaled to the point in the story they're at, but that the narrative will tell us more accurately whose supposed to be stronger than who. More accurate than their literal feats.
Like if Rayleigh showed up now, I think he would be doing equivalent stuff to gaban. And if Gaban was sitting at saobody, he would look closer to how Rayleigh did in the story 15 years ago. Cause that's what a "strong member of the rodger pirates" was depicted as at that time.
In the end, portrayal and statements are what matter. That's better than relying on feats that are, for the most part, inconsistent.
That's exactly why Kaido is one of the characters who benefits the most from this line of reasoning. If Oda's portrayal and narrative statements carry more weight than inconsistent feats, then very few characters have a portrayal as overwhelmingly dominant as his.
"In a one-on-one fight, always bet on Kaido." "The World's Strongest Creature." "The strongest pirate." "The invincible Kaido." Those aren't just random hype statements. They're the way Oda consistently chose to establish Kaido's place in the story.
That portrayal is also reinforced by how other characters react to him. An Admiral openly admitted he stayed away from Wano because of Kaido. The World Government, including the Gorosei, also avoided confronting him directly while he ruled the country.
If feats change depending on what each arc requires, then narrative portrayal becomes the most reliable form of evidence. And by that standard, no character has been portrayed as more dominant in one-on-one combat than Kaido. Kaido remains the standard by which Oda measures power in one-on-one combat.