Update default scene settings object creation to include exp fog and all relevant component.

ScriptableRenderPipeline/HDRenderPipeline/Editor/HDRenderPipelineMenuItems.cs

             Undo.RegisterCreatedObjectUndo(sceneSettings, "Create " + sceneSettings.name);
             Selection.activeObject = sceneSettings;
             var volume = sceneSettings.AddComponent<Volume>();
+            volume.isGlobal = true;
+            volume.Add<HDShadowSettings>(true);
+            visualEnv.fogType.value = FogType.Exponential;
+            volume.Add<ProceduralSky>(true);
+            volume.Add<ExponentialFog>(true);
         }
 
         class DoCreateNewAsset<TAssetType> : ProjectWindowCallback.EndNameEditAction where TAssetType : ScriptableObject

ScriptableRenderPipeline/HDRenderPipeline/Sky/AtmosphericScattering/ExponentialFog.cs

 {
     public class ExponentialFog : AtmosphericScattering
     {
-        // Exp Fog
-        // Exponential fog
-        public MinFloatParameter fogDistance = new MinFloatParameter(100.0f, 0.0f);
+        public MinFloatParameter fogDistance = new MinFloatParameter(200.0f, 0.0f);
-
             cmd.SetGlobalVector(m_ExpFogParam, new Vector4(Mathf.Max(0.0f, fogDistance), 0.0f, 0.0f, 0.0f));
         }
     }

ScriptableRenderPipeline/HDRenderPipeline/Sky/AtmosphericScattering/LinearFog.cs

     {
         private readonly static int m_LinearFogParam = Shader.PropertyToID("_LinearFogParameters");
 
-        // Linear Fog
         public MinFloatParameter    fogStart = new MinFloatParameter(500.0f, 0.0f);
         public MinFloatParameter    fogEnd = new MinFloatParameter(1000.0f, 0.0f);
 
-
-            // Linear Fog
             cmd.SetGlobalVector(m_LinearFogParam, new Vector4(fogStart, fogEnd, 1.0f / (fogEnd - fogStart), 0.0f));
         }
     }