Horizon Forbidden West

To get this trophy, simply complete the game a second time in New game+.

To reduce the number of Playthrough, pair this trophy with Completed Ultra Hard  

In order to start a New Game+, you must complete the game once and then, go the The Base and search for the little statue in the center of it. You will see an icon on the compass, with a + on it. Follow it and start the game again. You will be able to select the difficult after that.
Once you start the New Game+, just skip the tutorial and rush through the game focusing only on the main missions.

In New Game+, you will carry everything you got from your previous run: level, abilities, weapons, resources and also the key item.

Unfortunately, the overrides will not carry over New Game+, so you will not be able to use the Sunwing until you unlock it at the end of the game.

Also, you need to reveal again the whole map.