MTL - Top Savvy: Starting From Basic Boxing - Chapter 192 The three principles are close by, and the compound magic is earth-shattering!

Master martial artists were beings that no one can obstruct. A martial arts expert has been reborn into the body of a genius whose cultivation has been abolished and has been abandoned by a woman. Therefore, he starts cultivating the art of Xing Yi Quan, producing a solar system within his dantian. His innate talent tramples over all the geniuses, and even the geniuses among geniuses.

His powerful spirit and ruthless and ambitious nature, no matter who he is reborn into, will never change! Slaughter is instinctive, being cold-blooded is his personality, exterminating an entire family is only a means towards a goal, cruelty means infamy, and chasing after women… is just an interest.

- Description from Novelupdates

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.

After suddenly dying while trying to meet a deadline, Gu Huai transmigrated and became a non-human race.

This race is cruel and cold, making them feared and shunned by everyone in the interstellar world.

As the new king of the race and facing the group of parents who see him as a baby, Gu Huai said he was under a lot of pressure.

- Description from Novelupdates

When Orion is mysteriously transmigrated into a primitive world where sex and other goods and services can be bartered for, he is determined to make the most of his second chance at life.

But as he delves deeper into this dangerous world filled with temptation and magic, Orion must use his wit, charm, and thirst for adventure to survive and make the most of his second chance at life.