As per the manual from https://www.trainsimcommunity.com/mods/c3-train-sim-world/c105-ini-tweaks/i3889-tsw4-lighting-graphic-enhancement-version-32 by JetWash.
It includes making some changes to engine.ini, Godmode.save, installation of Reshade.me and changing resolution to enable NIS (NVidia Image Scaling) in NVidia settings.
I saved a backup of my previous engine.ini in case I don't like this new one.
Also installed vegetation update mods for TSW4 from: