He'll be world-class? He's the definition of world-class already. Not gonna say he's THE best player in the world, that can be argued all day, but along with Mbappe and Haaland he's the future of football in the same way Messi, Ronaldo and Greizmann have been for so long.
What he's doing for someone that's not even 21 until the middle of next year for a club the size of Real Madrid and their stature is ridiculous.
He's certainly hit the ground running. He's a generational talent but I'll hold off on world class until he's done it for a few years at the top level. Pogba was potentially world class but I certainly wouldn't class him as that as he only showed it in flashes and his reputation was enhanced by being in an exceptional French side.