This kid's brain isn't even fully developed, and I doubt if his IQ . . . is that high.
Carlsen has an amazing memory. That alone will help out with some portions of an IQ test.
He speaks multiple languages and works with logic problems all day. That will also help.
It would be strange if his IQ were only 100.
But people who think you need 160 or 200 to be smart don't know anything about it
If Carlsen were 1 or 2 standard deviations above average that would pretty expected I think.
This kid's brain isn't even fully developed, and I doubt if his IQ test scores, even adjusted for his age, but especially if results were directly compared with adults, is that high. Asked if he was a genius, he said something like, "No, I'm just very good at what I do."
https://youtu.be/_308KNAuFkg