There is a novel about time travel. The female protagonist is called Qian Duoduo, and the male protagonist is the Regent Prince called Zhan Beilie.

Qian Duoduo had transmigrated to an ancient dynasty and became the emperor's younger sister. She met the regent, Zhan Beilie. The two fell in love and joined forces to govern the country, but the power of the regent continued to expand, eventually triggering a thrilling war. The title of this novel might be " The Regent's Favorite Concubine "," The Imperial Sister is Poisonous: The Regent's Lazy Concubine "," The Regent's Concubine: The Regent's Fight ", etc.