These patches are made using the addresses posted by Reddit user OnkelJupp to remove ultra-widescreen pillarboxing from Horizon Zero Dawn without the need for manual hex editing.
Unpack the archive using the password pcgw
Open the desired patcher and navigate to the game folder where HorizonZeroDawn.exe is located and click Start
Launch the game and set the aspect ratio in the settings to Auto
Included resolutions are 2560x1080, 3440x1440, 3840x1600, 5120x2160, 6880x2880 and a combined patcher for 32:9 aspect ratio resolutions 3840x1080 and 5120x1440.
If a desired resolution isn't included with the patches, test use this calculator by first entering one of the included resolutions and then entering the desired resolution. If an exact match is achieved (such as 2560x1080 matching with 3840x1620), you will be able to use the patch compared against without issue.
Tested on the Steam version of the game on versions 1.00 and 1.01, however there should be no issue with using these patches on the Epic Games Store version.