Go to https://reshade.me/ and download the latest version of ReShade and install it into your game folder. Then go to -https://www.nexusmods.com/assassinscreedodyssey/mods/18?tab=files
- and download the zip folder containing the "reshade-shaders" folder and the configuration .ini file and copy and replace into your game folder. The game then automatically selects the only available configuration file.