Doe Princess Twilight Sparkle rule a kingdom yet?

If you want to know, yes. She owns the Rainbow Castle with the rest of the mane 6.
If you mean like a quiz question, then make it as a quiz question.

No, she doesn't. The little town of Ponyville is just a little town, she has no ruling experience, and I don't think she'll have what it takes to rule major empires.