Xu Lu transmigrates to the Great Qin Dynasty, only to discover that the body he's transmigrated into belongs to Xu Fu, at just the right time: before he sets sail to seek immortality pills.
Fortunately, he activates the Do as You Please System. As long as he acts as he pleases, he'll receive massive rewards.
(I don't know much about Qin Dynasty history. This isn't a historically rigorous transmigration novel, just a fun power fantasy.)