The social construct of race is which features we consider important enough by which to categorise people. So in the USA, this is white, black, asian or hispanic. Maybe native. Those categorisations are based on real observable traits, but we could choose other categorisations. It notably groups together traits which we can easily distinguish and pull out as subdivisions, such as south-east Asians.
We could redraw these groupings: we could for example together north Africans, middle-easterners and Indians, separating out those from southern and central Africa. We could separate Europeans so that Scandinavians, Finns and Slavs are together, separately from western and southern Europeans.