Here is just a simple breakdown of my latest project Before the Storm. You can find the full project here : https://www.artstation.com/artwork/Xnmral For this project I used UE 4.26. All the vegetation was done using reworked atlases from Megascan or random google photos, processed with Photoshop and 3dsmax and then sent to Speedtree for the final pass and baking. Then the trees and plants were all done in Speedtree using those atlases. In total I created around 50 unique vegetation assets. Rocks were sculpted in Zbrush and are using a shader combining 3 rock materials done with Substance Designer, all combined with dirt, wetness etc through RGB masks and vertex painting. Buildings are using the same kind of shader. Terrain is using Megascan materials reworked using Quixel Mixer. I used the "new" UE sky atmosphere and atmospheric clouds for the sky in combination with a light function adding moving cloud shadows. all the lighting is dynamic. For the village assets, I simply reused most of the ones I did for my japanese village scene, full project here : https://www.artstation.com/artwork/WKd0w3 I hope you'll like it 
Rock material parameters part 1
Rock material parameters part 2
Vertex paint to add/remove wetness and top material (either moss or orest floor)
Virtual texturing for rock blending
Spline blueprint for rice fields + virtual texturing for blending
Background clouds
Clouds shadow light function in action