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.
In the Texas, you can ask for “half and half” tea. You’ll get a mixture of sweet and unsweet iced tea. In a huge glass with plenty of ice. And free refills.
If you want hot tea, you need to ask for hot tea. Most places will bring you a couple selections of bagged tea and a too-small pot of not-hot-enough water. Hotel restaurants are known for bringing out a huge caddy of various tea bags for you to chose from. If you want milk/cream in your hot tea, you’ll have to ask for it, it’s not assumed.