While the Witcher 3 Patch 4.03 introduced Intel XESS as well as a dedicated Steam Deck preset, the settings are not as impactful as we'd hoped.
The PC section specified the following changes:
Fixed an issue with ray-traced vegetation shadows “popping”, depending on Geralt’s proximity and angle.
Fixed an issue where repeatedly disabling and enabling ray-traced reflections and shadows could cause black shadows to appear at the edge of objects.
Addressed the issue where the DirectX 11 version of the game could crash on launch or after loading a save on certain AMD GPUs.
Added support for Intel Xe Super Sampling, an upscaling technology that uses machine learning to improve performance and image quality.
Fixed some lighting issues with Screen Space Reflections when ray-traced global illumination is off.
Performance improvements to ray-traced global illumination and ray-traced reflections.
Fixed an issue where purple splashes could appear on the screen when riding Roach through puddles of water.
However there was also the new Steam Deck preset added, which did enable XESS for me at first, but the performance hit vs quality difference over FSR 2 quality, just wasn't there.
