Hong Kong. It depends on the establishment.

In big Cantonese restaurants, tea is the very first thing you have to choose, and you are expected to know what tea varieties there are. They then brew and bring you the tea in a white porcelain pot, and can top it up with water upon request (or do it yourself since water is always served alongside the tea). I generally like 鐵觀音, but my dad prefers 普洱. The tea is unsweetened, and if you ask for it sweetened or put sugar in it, well idk what happens but you'd probably get laughed at and kicked out.

In smaller diners, you often can pick the type of tea you want from a menu, though those are often not traditional Chinese teas, and are hot and sweetened by default, though you can always ask for it unsweetened or iced. Milk tea is always available (I can only assume under threat of public boycott). Depending on the diner, various fruit teas would also be available.