Hunter of Mysterious Creature - Chapter 448 - 69: "Regurgitation

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.

The only way to stop the earth’s doom.Is to seduce the girl who is the student council president.

When Yao Shen, Patriarch of the Heavenly Sky Sect, ascends and regains memories of his past life on Planet Earth, he realizes that he can no longer allow himself to accept the cruel and violent ways of Eliria, the realm of cultivation. So he decides to change it. It was time to found a new sect. One based on the values of honor and equality over senseless violence and discrimination. A sect where all, from the mortal farmer’s son to a sect elder's daughter, were held accountable to the same rules. Welcome to the Modern Sect.