We're denying that Luffy has gotten more and more attention as he enters a typical chosen one narrative ? Ok
Luffy always had attention. Every plot ploint, every storylines since the beginning of One Piece have served or were here to enhance the protagonist and the thematic of the story. That's how we create a story.
Very roughly:
The protagonist (or the thematic of the story that is attached to the protagonist) are in the center of the story's structure during its creation. You can take those lines as the timeline of the story. At the beginning you are on the outside of the lines and the more the story advance the more the story will refocus on the protagonist in order for all the parameters of the story to create one unique structure at the end. A bit like a inverted BIg Bang. The story will truly shine when everything here will go back together.
So the fact that you are feeling that we are more and more focus on Luffy is due to the fact that the story is starting to shrink on itself. At the end, Luffy, the thematic of the story, the characters, the world, the power setting, the message and the antagonists will make one single bright entity that will make the story unbelievably expressive.
There is a visual story that literally do that on screen:
Harry potter VII (the last movie)
This scene is the moment and place where everything connect, the plot lines, the powers.. EVEN the protagonist and the antagonist, simply because this moment is when the protagonist and the antagonist
are the closest to eachothers, thematically: