Sorry, I got the settings for FSR and DLSS mixed up. It seems that DLSS has not provide quality settings directly, so I take a look at the source code of DLSS. It seems that the quality is directly decided by your screenpercentage.
And DLSS provide many blueprint callable functions, you may call them in your level blueprint.
You may try
Set DLSS-SR Mode in your level blueprint. Console variable r.NGX.DLSS.Quality may also help. But I haven’t tried them.The code snipaste is taken from DLSS\Source\DLSSBlueprint\Public\DLSSLibrary.h, based on DLSS 3.5.10