The Ultra Quality preset is mentioned in the UE5 documentation, but it is unclear how it differs from the Quality preset or when exactly it is going to be activated for end-users. The latest UE5 build also features a new 2.2.9.0 DLSS version that apparently comes with worse image quality compared to version 2.2.6.0.
https://www.notebookcheck.net/Nvidia-could-soon-introduce-an-Ultra-Quality-preset-for-DLSS-new-version-2-2-9-0-spotted-in-UE5-with-worse-image-quality-than-2-2-6-0.548456.0.html