The variation of IQ among any population follows a bell curve. The center of that bell curve it what is different among races.

https://www.scribbr.de/wp-content/uploads/2023/01/Normal-dis...

So yes you can very much find black people who are smarter than Asians and vice versa but the generality (aka the mean, aka the center of the bell curve) will be different for races.

>But the _variation_ in IQ in a population is not explained by genetics.

This is not proven to be true. The most likely explanation is that variation in a population can be explained by both environment and genetics.