Terrain like Cube World

I always wondered how Cube World or Trove had such a nice world ... is there any asset or guide how to create something like that?

 

You could start here:

 

You could start by checking how procedurally generated worlds are made, to begin with. How are they implemented, how do you generate a natural-looking world...
To make it short, Cube World, Trove and Minecraft use procedural generation and chunks.

You can check basic procedural generation with Perlin noise. Applied to Trove, it would go like that :
A Perlin noise is a 2D array of random values between 0 and 1. For a very simple terrain generator, you can say that every number in the array corresponds to one cube height on your Trove map.
That's for one chunk, a set piece of the terrain of, say, 16x16 blocks. In order to generate an infinite terrain, you would calculate the perlin noise of a given chunk, then compute the terrain.

This video helped me understand how it works :