To reduce Unity assets 3D models for Unreal, export the model from Unity as FBX (with textures/materials included) and use Unreal’s Static Mesh Editor to lower polygon count, create LODs, or simplify materials.
Unity’s shaders don’t work natively in Unreal, so replacing them with Unreal’s PBR shaders cuts complexity. For extra reduction, use external tools like Blender to pre-simplify polygons if Unreal’s built-in options aren’t enough.
If you’re new to Unreal, start with small assets (e.g., props) and try the "Optimize Mesh" tool in the Static Mesh Editor—it’s a simple way to test reduction without extra software.