As usual, play with the settings for lower power usage, adjust draw distance and detail to medium. You can get 12Watt / 3:45h of gameplay and still keep very good graphics (8xAA, FXAA High, 4x Aniso, Low Shadows, Low Occlusion, High Backdrop, Godays, Vol. Lighting, etc). Potential for even better battery lowering graphics.

Add launch parameter "-noblur" and use Proton Experimental to avoid the big white blocks when shining the flashlight on enemies