If you describe a person as a drag, it means that they're boring and unpleasant. It's true that you don't hear that very often. It's more common to describe an event or task as a drag. "Sorting laundry is such a drag", for example. We don't say this that often, since it can sound a little critical and/or whiny, but we definitely do say it. Being "in drag" is different, and is usually marked by the preposition "in". "He's in drag" means that he's wearing women's clothing specifically for fun or to entertain other people. We can also combine drag with other nouns, as in "drag show" (in which people in drag perform), "drag queen" and "drag King". "Drag" is a little different than cross-dressing, since "drag" is specifically intended as a performance, and cross-dressing usually isn't. Sometimes it's about expressing yourself, sometimes you just like the opposite sex's clothes. It's very common for women to wear men's clothing, for example.

You can use "drag" for a boring person but I think it's more often used for a boring situation, such as " I had to wait half an hour for the train again! What a drag!" It may not be very common but I've heard it quite a few times, in conversation more than on TV. A man who wears women's clothes to entertain other people is a "drag queen". We also say "he is wearing drag". If someone wears clothes of the opposite sex for their own pleasure, we say "cross-dresser" or "transvestite"!

Drag also means to dress in clothing of the opposite sex for the sake of entertainment. Like ' One of my friends is a drag queen.'

Describing something as a 'drag' to mean boring is a meaning that isn't really in common usage now - it stopped being used somewhere between the 90s and 2010. Dressing up in drag - meaning a man wearing clothes associated with women, is still sometimes used, although is falling out of fashion. The term 'cross-dressing' is also sometimes used for the same meaning. I'm sure most languages have these things - phrases that used to be common, but aren't any more now.