The problem here for me is that her personality makes it look like either she's being extremely oblivious or extremely malicious and not in a particularly sexy way.
Like, she's not really presented as an intentional dommy and even when she does (like that scene where she holds him down and call him weak) it comes in a way that feels malicious but, again, not in an intentional way.
It ends up with her being an extreme bully while not really feeling like she's even intentionally a bully (and I get it's because she's obsessed with him, like you said, it's part of the premise). But with how it plays out, It's kinda early Nagatoro but with a sense of obliviousness that clashes with the idea. Simply put, she's too dumb to even realize she's being a massive dick.
I'll continue reading because end of the day when it comes to the actual fetishes presented this is nearly a perfect circle with my preferences, just that scene of being held down is shit I've literally paid real life muscle girls to do to me, if she had visible muscles and 20 extra IQ points this would be actual peak.
Edit half an hour later: Ironically, I straight up just now read a recently released hentai that's basically the idea of this manga to a tee (obsessed large sister manhandles dude) that just does the same thing better and while I'm not sure if I can straight up link or provide launch codes, should be easy to find. Kinntarou also released part 4 of his work and the dude is literally choked and punched in the face and, again, better execution personality wise of a mean, overpowering girl than this and both serve as a better example of what I'd wished this could be, since end of the day author has the heart in the right place.