No, generally, iced black tea sold in the market is added with citric acid besides black tea and sugar, so it will taste a little sour instead of just adding sugar to it.

I think if you want to make your own iced black tea, you can buy Lipton's bagged black tea, and add appropriate amount of sugar and milk according to your taste after soaking it into black tea. This will make the milk tea more suitable for your own taste and purer than what you drink outside.