Netherborne [An OP Monster Isekai] - Chapter 60. Axon

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 oldest myth between heaven and earth reappears in the world, countless spaces begin to slowly interweave, and the dark side of the world quietly emerges.

Advocate the friars who are weak in flesh and blood and eternal in spirit. Showing a tyrannical body, there is my invincible martial artist.

Looking at the changes in the world, Lu Ren exhaled in a panic.

“Ding, because of your uninterrupted breathing for 26 years, you suddenly realized something, and successfully realized the breathing technique.”

Hearing the prompt sound in his mind, Lu Ren waved his sword hesitantly.

“Ding, because you were blindly poking a few times with your sword, you suddenly realized something and successfully learned basic swordsmanship.”

After a long time, he looked at the army invading from another world, raised his long sword and slashed it out.

In an instant, the endless air waves rolled back, and the mountains and rivers where they passed collapsed, and the rivers fell.

Then the army was annihilated and bombarded towards the different world. The entire other world was completely shattered by the explosion of infinite fire, and slowly disappeared into the air.

- Description from novelbuddy

The more ruthless the Palace is, the more miserable the loser will end up—this he understands. But what he does not understand is, why the brother whom he lived together with peacefully in the past, would so heartlessly humiliate him today. Asking him to beg for mercy, asking him to succumb to his knees, and even… asking him to tactfully entertain him. “Yong Shan, ah, Yong Shan, as of today you are the one who qualifies to succeed as a Crown Prince, what exactly is it that you want?”

For the past 16 years, Yong Qi’s gaze was never set on him. Despite being twins with his younger brother, Yong Lin, Yong Qi has always been directing his smile and laughter towards Yong Lin, and to him, Yong Qi deliberately alienates him. He does not understand, they have the same features and looks, and he obviously is his brother too, but why won’t he be intimate with him… as if he is humiliating him. “Yong Qi, ah, Yong Qi, why won’t you understand, what I want is very simple…”

- Description from Novelupdates

Lingyun, a fierce and savage cultivation genius takes over a dead teenager’s body. Coincidentally, they are both named Lingyun. Set in a alternate version of the 21st century, teenager Lingyun has been killed by someone with a grudge.

- Description from Novelupdates