I Awakened as an SSS-Rank System Maker! - Chapter 1 - Systems Creator (SSS-Rank)

After getting betrayed and killed by the only person she’d loved, Miss Shang wakes up in the body of the cowardly crown prince Shang Wuxin, who, due to her own circumstances, was actually a girl cross-dressing as a boy. After inheriting the crown prince’s memories, Shang Wuxin has three things on her agenda:

1. Clean up the house

2. Gather loyal followers and soldiers

3. Get the throne

- 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.

There are two women with the same name in the entertainment industry, one is Qu Xizhi and the other is Gu Xizhi, because they debuted at about the same age, they are often compared.

There are rumors in the rivers and lakes that the relationship between the two is extremely bad…

- Description from novelbuddy

I turned my assassin into my maid with the power of money! Money is all-powerful!

It was a world full of swords and magic; Lawrend was the son of the wealthiest merchant in town. Since the age of 7, he had been having dreams. A dream about a past life in a modern civilization where monsters are nonexistent, and humans dominate the world. Lawrend saw Iron birds, Magical bricks that display moving paintings, Thunder wielding, and many more.

There was a scene in one of the dreams that made Lawrend’s heart beat fast. A row of a dozen maids bowing in front of him. Each dressed in a french maid outfit.

Something awakened inside Lawrend when he had that dream. A fervent desire to have his very own Maid Harem!