Here is a small environment practice project that I've just finished. It is based on an awesome concept art from Lim Hannah (Tomb of the Ancient King): https://www.artstation.com/artwork/o54PJ
All the props were made in ZBrush (high-poly) with retopo/UV in Maya, baked in Marmoset Toolbag 3 and textures were painted in Substance Painter. The scene was assembled and lit in Unreal Editor 4.
Total polycount for the entire scene is ~17k tris.
The original textures are mainly 2k or 4k. Marmoset Viewer compressed them quite hard, just to fit the 15mb cap. They are much crisper in UE4. Of course, the textures resolution is a bit overkill. They can be easily compressed if needed (or exported at a lower resolution from Painter).
With everything maxed out the scene runs at 120 fps cap with stationary lights, and ~90 fps with dynamic (movable) lights and raytracing enabled (smoother dynamic shadows, etc). Quality preset is Cinematic, 1080p resolution, GPU 980ti.