The Clan Master Can't possibly Be A Mortal - Chapter 998 - : Evil Cultivation Technique, Third Turn Quasi-Saint, Missing Person

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.

Playing under the plum trees and riding on bamboo, those were the days of joyful play. It was when they first met.She was not shy but innocently charming, standing before the breeze with her hair flowing, her complexion as creamy as curds.After waking up, Xu Qingfan had returned to 20 years earlier, to the year 2002.That year, the sky was very blue, the clouds were very white, and the wind was very noisy.That year, his Childhood Sweetheart hadn't gone abroad, their parents hadn't gone grey, and he hadn't the worries of being unaccomplished.That year, he was six, she was five, and they both could fully experience the climate as snowflakes blossomed.PS: This book is also titled “Help, I'm Surrounded by Childhood Sweethearts” and “I Have a Little Too Many Childhood Sweethearts.”

Carn wakes up from a vivid dream where he spent a thousand years as a gargoyle, guarding a demon lord's tomb.In this dream, he possessed supernatural powers, including the ability to teleport and instantly kill anyone within range who broke eye contact with him. Heroes, saintesses, adventurers, all fell before him.When he returns to his normal life, things take a strange turn. Carn realizes he still has the gargoyle’s powers, and the world he has woken up to seems different.But adjusting to the new reality is not the real issue. Carn brings back something nobody in this world has imagined. Not only he imports his powers to this alternate Earth, but he also carries over his gargoyle instinct and his hobby. He loves snapping human necks.Whether it's ordinary humans, explorers, super soldiers, cyborgs, mutated beasts, monsters, or mysterious entities from other dimensions, Carn eagerly anticipates snapping their necks, one neck at a time...In secret, of course.

After what seems to be a plane accident,

Su Bai Master Su was seized of his power and unexpectedly reincarnated onto a cowardly distant nephew.

Who said that you will lead a dull life after rebirth?

The ‘Jade-Faced Yama’ who once ate both the black and white path

vows to take back the power that once belonged to him step by step.

Do you really think Master Su is a rice dumpling for everyone to push around when he does not display his wrath?

- Description from Novelupdates