The minimum solid angle in degrees that Unity uses for culling ray tracing instances associated with the Renderers in a Scene.
If the projected solid angle of a Renderer relative to cameraPosition value from RayTracingInstanceCullingConfig.lodParameters is smaller than minSolidAngle then the Renderer is not added to the acceleration structure.
To enable solid angle culling, use the RayTracingInstanceCullingFlags.EnableSolidAngleCulling flag in RayTracingInstanceCullingConfig.flags.
Additional resources: RayTracingAccelerationStructure.CullInstances.