Thanks. To complete the list, I found also:
culling of instanced mesh, put in console r.RayTracing.Geometry.InstancedStaticMeshes.Culling 0
screenPercentage r.ScreenPercentage 100 (or higher value)
Also try:
r.ForceLOD 0
foliage.ForceLOD 4 (or 0)
foliage.MaxTrianglesToRender
r.Nanite.MaxPixelsPerEdge