Invicinble Colorless Butler - Chapter 84 - 47

Reborn in the world of One Piece, I, Karl, was granted a unique “Gacha” System. Every five years, I get to smash a golden egg and pull a legendary prize.At age 5, I pulled the [Infinitely Evolving Monster Body]. As long as I keep eating, I keep getting stronger. The seas would soon fear another monster like Big Mom.At age 10, I pulled the [Sealed Mystical Spear]. A weapon capable of converting my stamina into a beam of pure light, capable of annihilating anything in its path.At age 15, I pulled my greatest prize yet. A card from another world... the legendary [Blue-Eyes White Dragon]!At age 20... the world was no longer ready for what I would become.My legend begins in the East Blue, but my destination is the heavens. They call me a pirate, a monster, a king.But my true title is... The Dragon Knight.

The heavens and earth change when the blood phoenix descends.

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.

What is a genius? Capable of comprehending any battle skill regardless of the skill itself and sweeping away the bottlenecks while cultivating a new technique; this is a true genius! He Yiming was originally an ordinary youngster in the He family’s estate with not too extraordinary aptitude in learning martial arts.