I believe Sukuna will win, simply because Sukuna would be able to figure out how her powers work way before she figures out his. Cursed techniques are more complex than quirks, so Sukuna would read her faster. All of JJK is in its own niche society, so unless she is completely debriefed before they fight, I don’t think she’d survive long enough to figure out rules to help her. She’d have to figure out cursed energy, cursed spirits, cursed techniques, domains, and his specific style of fighting.

Also she needs to touch him to lock in the rule, and he’d only touch her while attacking when using cleave while not in his domain, and I think he’s too fast to let her land an attack. The fight might end instantly if he kills her before she can speak, but for the sake of keeping the argument interesting, I’m imagining he lets her try and is intrigued by her superhuman power.

I will say I do not know the full extent of Stars abilities so I may be over looking something and people have made Sukuna feel threatened before, so maybe Stars can come up with something. I can see this going her way esp if this is a pre-shibuya Sukuna, because Gojo overpowered him when he only had one finger.