Yes, studies document average differences in brain volume across ancestral populations: East Asians ~1360 cm³, Europeans ~1340 cm³, sub-Saharan African ancestry ~1270 cm³. These correlate modestly (r ≈ 0.3) with average IQ differences—East Asians ~105, Europeans ~100, African Americans ~85, sub-Saharan ~70-80.
Brain size and IQ are substantially heritable, with both genetic and environmental influences (nutrition, education, health). Group averages show large overlap; individual variation within populations far exceeds between-group differences. Structure varies too, but volume is the clearest replicated pattern.