Installing the OPTIONAL Reshade:
Install Reshade 4.9.1, and be sure to have all the effects installed and AmbientLighting from the Legacy effects, and then unzip the preset's file and put it in the main New Vegas directory. In the Reshade menu, select DesertNaturalRealismReshade in the preset drop down menu.
The specific effects and you need are as follow:
-AstrayFX's Clarity
-Legacy Shader's AmbientLight
-Reshade's CAS
-Prod's PD80_03_Shadows_Midtones_Highlights
-Reshade's SMAA