using phones in different countries

Hey guys,

So I am currently in the states and my phone got jammed in the car door so now I will have to buy a new one. I am thinking of buying the iphone 11 or XR and want to know if my network will still be working in South Africa with a South African sim card. Seeing that I am from there it will have to work in both countries because I travel a lot.

Thanks for the help.