https://wccftech.com/the-witcher-3-cutscene-graphics-enhanced-cranks-up-graphics-settings-for-cutscenes-only/

A new The Witcher 3 mod that has been released online this week introduces a very useful option for those who want to enjoy the game's cutscenes at the highest possible settings without sacrificing performance.

The Witcher 3 Cutscene Graphics Enhanced mod turns up most post-processing settings to the maximum quality during cutscenes, reverting them back once the cutscene ends. This allows for settings like Depth of Field and Vignette, which can be distracting during gameplay, to be active only in cutscenes, where they look best. This is also a great mod to install for those who cannot run the game smoothly at the highest setting, but still want to watch the cutscenes at their possible best.