Days as a Spiritual Mentor in American Comics - Chapter 4384 - 3477: Midnight Sons (39)

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.

In the City of Crime, one law stands above them all: Only the strongest can live.

A genius talisman practitioner is reborn as a seven-year-old girl! However, her innocent appearance belies her vicious personality.

The arrival of origin ability era. Many berserk beasts spawned. Humans with superpowers blooming like mushrooms. Su Hao is just an ordinary 3rd year high school student who had mastered a lowly grade origin ability named
“Model analysis”.