There's a few measures of "IQ". The most common one today centers at 100, and defines a standard deviation of separation on the task of being "generally intelli

There's a few measures of "IQ". The most common one today centers at 100, and defines a standard deviation of separation on the task of being "generally intelligent" as 15 points. An IQ of 263 is a claim that that person is nearly in the 11th standard deviation above average, which corresponds to a claim that they are roughly 1 out of 6 × 10^26. This is not a plausible claim. The number is meaningless. IQ tests would have to be constructed to measure somewhat similar intelligences of a population large enough to have a meaningful "population". The scales could then potentially be roughly calibrated to each other, but they wouldn't really be translatable. The task of constructing them would be up to the intelligences in question. It is possible no such measure could exist; as the "size" of the intelligence increases, the number of degrees of freedom of "intelligence" almost certainly increases, just as we can be good at bugle but terrible at piano as humans (and that's already a fairly microscopic focus in the grand scheme of human activities), but those statements are almost meaningless to ask about a raccoon, even if we give them raccoon versions of the instruments. Even at human scales, while IQ seems to measure something, we can see the measure is getting fairly strained. You probably need an increasingly multidimensional "number" as the intelligence continues to scale up. As for what intelligence is, all we have are other hypotheses that are on the one hand clearly related to the question at hand, yet on the other, not the answer. Arguably, AI like GPT-3 is also a measure of our best definition of "intelligence". If we could completely clearly define it, we could probably implement whatever it is we defined.