Valerian, The Legendary - Chapter 299 - The Guardian & The Diversity.

A scientific genius named Thomas Harrier was transmigrated to an imperial prince body after a car accident that took his life. He found out that he is in a world similar to our own with a timeline akin to early twentieth century. The body that he is occupying was the imperial prince of a failing empire who suddenly rose to power after a successful assassination attempt of his father. Unaware that the attack is just the beginning of what is to come. He faces many challenges throughout. Will Thomas Harrier be able to live his second life in peace while running an empire and getting it back to its former glory? Or will he succumb into a conspiracy lurking within the country's borders?

Expect some:

Cold war era techs.

Super battleship with advanced electronics, propulsion, and fire control systems?
Helicopters?
Missiles?
Modern medicines and equipment?
AC-130?
A nuke?
Challenger or Abrams or Leopard?
F-4 Phantom or MIG-21?
Colored TV's.

Everything!!!

PS. Cover not mine, I just found it on google.

Coming to my senses... I find myself a desperado.In the depths of azure, black sails flutter.Treasure gleams, blades ring out.Pillage, slaughter, irreverence towards the gods.Youth fades swiftly, all but meat and wine for pleasures.[Slice of Life][Romance Simulation][Business Simulation]

Dying in a tragic accident Marcus Ferrous gets transferred to a fantasy world of monsters and magic, except when he arrives contrary to what he expected he is now level one and a ghost. Left with nothing on a strange new world, Marcus will struggle with everything he has on his journey to get stronger and uncover the secrets of his new world.

Wei Ruo, a highly skilled doctor, was time traveled as a female supporting role in a novel. She was left neglected in the countryside for ten years and returned back when she was thirteen years old.

Seeing that she only knew how to grow flowers, grass and vegetables all day long, everyone thought that she was a peasant woman.

As the female supporting role, Wei Ruo did not want to fall in love with the male lead, nor did she want to compete with the female lead. All she was thinking about was to make money, make money, and make money!

When the fake daughter was still worried that Wei Ruo’s return would affect her status, Wei Ruo had quietly saved up a private fund.

When the fake daughter was still trying to attract the male lead’s attention, Wei Ruo had already made a big fortune.

If you want money, you have money, if you want food, you have food, The shop was opened one after another.

Later, her brother became the first minister, her father became the general, and the one sitting on the emperor’s chair was her husband.

- Description from Novelupdates