One Piece: The Devil Fruit Collector - Chapter 120: The Sun Rises Reborn from Fire and Light

Gripes have their origins and debts have their creditors. We haven’t crossed each other in days past or present, nor formed any grudges. I am but duty-bound to carry this out, so apologies in advance!

In his past life, Yang Chen was a gentle person who was oppressed for his whole life.

Now that he’s reborn, he chose to become an executioner and severs ties and grudges with his executioner’s blade, killing all that climb onto the Immortal Executioner’s Platform!

Heads will roll! Humans’ in the human realm, demons’ in the demon realm, devils’ in the devil realm and immortals’ in the immortal realm!

- Description from novelupdates

In the early world of immortal cultivation, there was no physical cultivation among immortal cultivators. And a top bodybuilder who came from the earth has opened up a new path here and became the ancestor of physical training.

- Description from novelbuddy

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 a world where villains are crafted, not born, Vyan's life takes a detour from dull to downright dramatic faster than he can say “abracadabra.”Meet Vyan, the most ordinary knight in the realm, with all the magical prowess of a damp sock. Loyalty? He's got it in spades. Betrayal? Well, that's the surprise twist in his not-so-fairy-tale life.Framed and forsaken, Vyan is left with nothing but a grudge and some pretty gnarly scars, courtesy of his once-master, Iyana. Oh, did he mention she is the daughter of a marquess and the object of his unrequited affection? Talk about adding insult to injury.Just when he is ready to unleash his inner berserker, a butler comes along with news that makes his hair stand on end: Vyan is the last heir of the Grand Duke's mage dynasty!With power crackling at his fingertips and more mana than he can shake a wand at, Vyan is ready to show the world what happens when you underestimate the underdog. Will Vyan rise from the ashes like a phoenix, or will he crash and burn like a fire-breathing chicken? There's only one way to find out.