Logicality through pure realism doesn’t count.
It can be really fun to take fantasy fiction to the next level of world-building: being fully logical. Sure, maybe your fictional world has levitating cats, but how do they do it? Are the physics of your world different from ours? How does that impact other things, does gravity still function as is our norm? If cats can levitate, couldn’t science extract their powers to make hover-cars? On and on.
A zombie virus is making the rounds, and it’s hella effective. But why doesn’t their flesh rot off their corpses? Shouldn’t they be a bunch of skeletons? How does the virus work? Why wouldn’t it infect animals as well? Birds can get infected, so the spread should be portrayed many times faster. How does the virus operate, can it be found in a zombie organism’s feces? We’d be wiped out before you could double-check.
What about dragons? Do they fly? How can they? How do they keep their body temperature up, if that’s even how they produce flames. What’s the evolutionary purpose of that, anyway? And why are they so obsessed with gold and other shiny loot? How terrible is their gambling addiction?
You can’t bring your world-building to 100% if you can’t answer those kinds of questions. Not that it’s needed for a good story though!