Time for a good Enzo long ass peeeaaak fiction.
I made a theory about Yuji's possible domain which would deploy not into physical space but mental space/landscape (the innate domain - Shōtoku Ryōiki).
The important point is that "regular" domain expensions (Ryōiki Tenkai) are literally the physical extension of the user innate domain. As we've seen, the "regular" DE weakness is precisely their physical spatial extension.
Wether it has a barrier or not, one can either counter it from the inside or destroy it from the outside.
On the other hand, a "reversed" domain extension by wich the user could literally hack his opponent innate domain by imposing his own would be impossible to couter/escape.
In other word a perfect mind trap/cage (which is Yuji's main and first ability from chapter one).
Now, assuming Yuji could do such a thing, what would be the use of it?
Remember that when Yuji and Sukuna first fought inside the later innate domain he was totally submitted to Sukuna's innate CT, reason why he had absolutely no chances to win.
But if Yuji can impose his own innate domain within Sukuna's, the later would be submitted to Yuji's innate CT.
In other words, the same situation but reversed.
But what could be Yuji's CT? And here the twist: his innate CT would "just" be his ability to hack ppl's soul/innate domain by imposing his own, canceling his opponent CT.
In this situation, neither Sukuna or Yuji would have specific CT (or RCT/simple domain or else), but just their CE and fight skills, allowing Yuji to fight Sukuna as if they were regular MMA fighters in an unescapable octogon with no CT tricks allowed.
A soul fight in wich only "willpower" prevails.
Last point: between Sukuna and Yuji, who has the most willpower? The bored emotionless nihilistic or the enraged angry one who wants to avenge his friends? Hope it was clear (sorry, I'm french).
No needs to thank me.
Just call me the GTOAT (greatest theorist of all time).
Thanks for your attention.
@notAfanboy I tag you as a fellow true Yuji supporter.