No, I didn’t. There are multiple ways to achieve this.
F. e. you can adjust the units of you project (dropdown menu under “Scene”) and try to build everything in real world scale.
However you can do this and/or you can just model lets say an island in a size that you fell comfortable with and then use this island as size reference for every other object to want to have in your scene.
Because of the earth’s atmosphere you have some sort of blueish mist the farther you look. In Blender you can achieve this through the mist pass (check mist in camera settings under display and then adjust start and end endpoint in the world settings under Mist Pass.
If you want to animate your scene choose either slow camera movements to give your scene this huge feel or place small objects for detail f. e. bushes, small rocks etc. in the foreground of your scene your camera can pass as it moves forward. This also helps to create the illusion of huge landscapes.
But the best way to find is out is research. Gather reference photos and videos on the internet (especially drone footage in this case) and examine why it feels so big. Is it the Light? Movement? Detail? Color? Foreground and background? parallax effect? Write down the most important points and recreate them. Trial and error 
