Huang, the longest river in the world, how to be an official?

Hello, in the TV series "The Long River of the World", Huang Chen is a wizard in river management. Qin Shihuang met Huang Chen while traveling incognito in the Yellow River, and was attracted by Huang Chen's talent in river management, so he recruited Huang Chen to manage the Yellow River. At first, the emperor wanted to give Huang Chen an official, but Jin Fu refused. Jin Fu thinks it's better to let Huang Chen be his own staff to manage the river.