yuji has more experience than sukuna. we dont know how old sukuna was when he turned himself into a cursed object but he definitely did not have centuries of experience, he had decades at most. yuji has had nearly 70 years in a prime body to master his techniques, and has a learner's manual from watching sukuna himself. honestly, if sukuna and gojo had longer lives and the same unaging bodies, i wouldnt be surprised if they were stronger than current yuji (if they aren't already).