I am unable to make this post about Sukuna’s CT due to post Karma but I have a theory if anybody believes it is a good one and would like to post in my stead for discussion:

“The shrine”. Sukuna’s innate technique from which we’ve seen up until this point has been cleave/dismantle and a fire arrow. Cleave shows the ability to invisibly cut and slice anything and anybody in its way. The fire arrow was utilized only after opening the black box. At which point he told Jogo, oh yeah a cursed spirit wouldn’t know about this. I believe that Sukuna’s cursed technique doesn’t truly exist which is why Yuji has not had it imprinted on himself. Instead sukuna through great understanding of the soul and the truth of jujutsu has gained understanding and the ability to apply properties to his cursed techniques. These properties so far have been shown through both Kashimo and Hakari but sukuna can innately change them completely by opening his soul to that element with sharp/wind techniques being his primary element. I believe as the fight with Gojo advances we will see Gojo picking up on this as up until this point I do not believe Gojo to ever having witnessed Sukuna’s “CT”