In the South East, they bring you sweetened (usually far too sweetened for my tastes) iced tea. This is amazingly universal.
I live in NC and have been probing the border for years.
For “nicer” restaurants, the universal sweet tea boundary seems to be precisely at the NC/VA border.
I live in Australia now but someone already had a good answer for Australia.
I’m from Indonesia and there it’s most likely sweet iced tea if you don’t specify anything. But I think it’s more likely they would ask, warm or iced, and sweetened or unsweetened. You’ll get black tea with sugar syrup, sometimes regular sugar for warm tea. Lots of restaurants would often have iced lemon tea, which is also sweetened but with some squeezed lemon.