One thing I've done when arguing with a person that insists race is real and meaningful is to ask the other person how many races they think there are.
It gets the gears turning a bit.
European, African, East Asian, Arabic, South Asian, Indigenous Australian, Indigenous New Zealander/Pacific Islanders (same or different?), North American Indigenous, South American Indigenous? are Mexico's Indigenous people the same race as Amazonians? Peru? Are they the same race as the Inuit of the arctic?