Someone know of a way to make a world generator made out of blocks but not only?

Someone know of a way to make a world generator made out of blocks but not only?
There is this way:

But then I can only use cubes as the mesh, and then for example if I want to add bushes to the terrain, I cant.

I know there is the way with Instanced Static Meshes but I cant figure out how to not cause a lag once a chunk is “being loaded”…

I feel like I will waste my time if I will continue doing that in the first way that I showed, there is gotta be a way…