1660Ti past 1.04 performance patch settings for 1440p:
Settings:
VSync: 60
Max FPS: On
set to: 60
Window mode: Fullscreen
Resolution: 2560x1440
FOV: 80
Filmgrain: On (helps actually quite a bit for the image to look more natural. Imho only turn off, when you are using DLSS (which would add too much blur if Filmgrain would be left on))
Chromatic Aberration: On
Depth of field: On
Glareeffects: On
Motionblur: Low (good setting for OLEDs with motion setting clear)
Contactshadows: On (has quite a big impact, but improves facial shadows, so you'd want it -- see other shadow settings as well, imho you can introduce 'too many shadows' making the game look a little worse (subjective) using other shadow settings)
Better Facelightinggeometry: On (untested, I always left it on)
Anisotropic Filtering: 16x
Local Shadow Meshquality: Medium (high is a performance hog and imho almost looks worse...)
Local Shadow Quality: High (mashed best with Contactshadows On. If you use Contactshedows off, set to medium for a more congruent image (imho)).
Cascading shadows - reach: High (adds to the games immersion, scene lighting gets much better)
Cascading shadows - resolution: medium (High introduces many additional shadows at close distance, sometimes making the game feel 'too dark', somewhat a performance hog.)
Distance Shadows resolution: High (didnt mess too much with it - lower setting probably would lower scene immersion)
Volumetric Fog Resolution: Medium (if its in the scene it might hog performance, but it makes particle effects look much nicer. See the end of this posting.)
Volumetric Cloudquality: Off (Took this hint from the Nvidia Experience settings.

)
Maximum Dynamic Decals: High (Ultra changes the lighting of the game significantly, and also has a tendency to make it look too slick, also Ultra is a performance hog. Leave this on high, imho)
Quality of screen space reflections: Medium (Allthough this very much strengthens scene immersion (would like to leave it on ultra

) this produces large framerate dips, once in the city/open world. Sad.

)
Volumetric dispersion: High (makes light on human skin look more natural (high already is the highest setting), always left it at high for obvious reasons)
Ambient occlusion: High (use High in combination with anisotropic filtering 16x, and medium with Anisotropic filtering 8x)
Colorpresicision: High (already the highest setting: You probably wont notice it on medium unless you do a direct comparison, but High just looks better (larger color palette).
Mirrorquality: High or Medium (both tank the games performance, so why not set it to high..

Single digit fps confirmed..

should only matter - when you are looking into a mirror)
Level of detail : High (Already the highest setting)
That should net you 30-45 fps on a 1660Ti with the fps hardly ever dipping below 30.
If you want the game to look quite a bit better, at the cost of some dips below 30 that are noticeable, Volumetric Fog Resolution: High would be my first alteration.
Have fun.
edit: Ups forgot to mention the resolution target. Its for 1440p.