Da Qin: I Want to Dominate the World

How should I put it, what would the time traveler do when he returns to ancient times? There are clear textbook instructions

The late Qin Dynasty and the late Yuan Dynasty are probably the only eras where grassroots rise to dominate the world. At the end of the Qin Dynasty, the nobles of the six kingdoms were weakened to the extreme, and the aristocratic families were not even a shadow. At the end of the Ming Dynasty, the aristocratic families were all weakened to the extreme. In another era, grassroots officials like Liu Bang and Zhu Yuanzhang would hardly have a chance to develop.