The Mad Tycoon of Rome - Chapter 278:

Science and Technology Library: The supreme state of science is theology; an accidental rescue, let Chen Mo get a technology library that collects endless technology, the story begins…

- Description from xbiquge translation

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.

Genius, antisocial, solitary, intractable , maniacal.

At the turn of every era, it is he who raises the flag of the rebel cross.

Winners take it all, losers take the fall.

He who brings order to a chaotic world, assembles talents and masterminds.

He who hides among the crowd, yet stands on the top of the world.

— The one and only, him.

- Description from Novelupdates

Alex Jin was just another overworked nobody until a truck crash sent him into the body of Valerian Nightshade—the cold-blooded villain from a popular fantasy novel. Destined to die early as the stepping stone for the “hero,” Valerian was powerful, rich, and feared… but ultimately doomed.That is, until the Villain Evolution System activated.Now, every villainous act rewards Alex with unimaginable power. Crush a rival? +100 Strength. Manipulate a noble house? Unlock a rare bloodline. Kiss the heroine meant for the hero? Well... let’s just say the rewards aren’t all measured in stats.To survive, Alex must outwit plot armor, bend fate, and ascend to the throne of power in a world that expects him to lose. But the deeper he goes, the more he realizes—being the villain might be the only way to save this twisted world.This time, the villain won’t die early. He’ll rewrite the story, one ruthless step at a time.