Author's Reincarnation in a Fantasy Setting - Chapter 242 One Tipsy Night

After the hard struggle of a post-80s Shen Feiyang, he met with a tragic car accident in his fifties. When he again opened his eyes, he did not see the white walls of a hospital, nor had he arrived at the netherworld. Instead, he had transmigrated into the body of the post-50s young girl, Shen Yunfang.He had transmigrated into an era where people could not get enough to eat or sufficient clothes to wear.Humph, such hardships could not defeat a wise woman who had battled through society for half her life. Watch as she, with a chicken in her left hand and a duck in her right, carries a chubby baby on her back and sings triumphantly along the way.

Xu Mo, a modern high school student was sent back in time to Jing Kingdom and found herself trapped inside of the body of a princess with the same name.

She had barely recovered when she learned of an unparalleled fiancé and in a daze, they got married. Then the stunning genius physician who normally does not pay attention clamoured to marry her. After that, there was a cold general, a flirtatious lord, a tsundere young master……

As it turns out, this was a male-dominated dynasty. Because the female population was sparse, the entire nation shared wives regardless of rank or nobility. Is it feasible for someone who wants to maintain monogamy in this dynasty?

- Description from Novelupdates

Frank, a mercenary known for his cold ruthlessness, decides it’s time to leave the bloody world of the underworld behind. But the underworld has no plans of letting him go. Relentless enemies from his violent past keep hunting him, and eventually, they succeed—Frank is killed.But fate has other plans. Instead of staying dead, he is mysteriously reincarnated into the body of a cop in a world filled with crime, corruption, and dark secrets. With the help of a strange, all-knowing system, Frank is given the chance to live again—this time, to prevent crime before it happens.

…but it seems pretty doable.