Just go to C:/User/your name/AppData/Local/Biomutant/Saved/Config/WindowsNoEditor and open engine.ini.
and opens the engine.ini

I enter everything here again for removing the motion blur, the last entry at the bottom removes the ugly fog, and you have a much better foresight in biomutant. The volumetric fog remains, I didn't deactivate it, otherwise some effects (weather) would be missing. The unreal engine 4 has 2 different nebulae. The latter corrects the too bright brightness.

Copy and paste the following:

[SystemSettings]
r.Streaming.Boost=4
r.Streaming.HLODStrategy=0
r.Streaming.DefragDynamicBounds=1
r.Streaming.MipBias=0
r.bForceCPUAccessToGPUSkinVerts=1
r.FastVRam.EyeAdaptation=1
r.ViewDistance=5
r.ViewDistanceScale=4
r.MaxAnisotropy=16
r.LandscapeLODDistributionScale=2
r.LandscapeLOD0DistributionScale=2
r.StaticMeshLODDistanceScale=0.50
grass.CullDistanceScale=3
foliage.LODDistanceScale=4
foliage.ditheredLOD=5
foliage.MinimumScreenSize=0.00000001
grass.DensityScale=1.0
foliage.DensityScale=1.0
r.HLOD.DistanceScale=2
r.ForceLOD=0
r.EmitterSpawnRateScale=2.0
r.MipMapLODBias=0
r.MaxQualityMode=1
r.DetailMode=2
r.MaterialQualityLevel=1
r.SkeletalMeshLODBias=-2
r.SkeletalMeshLODRadiusScale=0.03
r.LandscapeLODBias=-2
r.Fog=1
r.FogDensity=0.02
r.FogStartDistance=6
r.TrueSkyQuality=1
r.SkyLightingQuality=1
r.VolumetricCloud=1
r.VolumetricCloud.SkyAO=1
r.VolumetricCloud.SkyAO.Filtering=1
r.VolumetricRenderTarget.Mode=1
r.SkylightIntensityMultiplier=0.4
r.SkyAtmosphere=1
r.SupportSkyAtmosphere=1
r.SkyAtmosphere.LUT32=1
r.SkyAtmosphere.FastSkyLUT=0
r.SkyAtmosphere.AerialPerspectiveLUT.FastApplyOnOpaque=0
r.SkyAtmosphere.TransmittanceLUT.UseSmallFormat=0
r.SkyAtmosphere.AerialPerspectiveLUT.Depth=96
r.SkyAtmosphere.AerialPerspectiveLUT.DepthResolution=16.0
r.SkyAtmosphere.SampleCountMin=64.0
r.SkyAtmosphere.SampleCountMax=128.0
r.SkyAtmosphere.DistanceToSampleCountMax=128
r.LightFunctionQuality=1
r.ShadowQuality=4
r.Shadow.CSM.MaxCascades=10
r.Shadow.MaxResolution=4096
r.Shadow.RadiusThreshold=0.03
r.Shadow.DistanceScale=3.0
r.Shadow.CSM.TransitionScale=1.0
r.DistanceFieldShadowing=1
r.Shadow.PerObject=1
r.AllowLandscapeShadows=1
r.Shadow.AllowForegroundShadows=1
r.Shadow.PreShadowResolutionFactor=1.0
r.Shadow.FadeResolution=0
r.Shadow.MaxPointCasters=1
r.Shadow.CSMDepthBias=20
r.AmbientOcclusionLevels=2
r.AmbientOcclusionMaxQuality=100
r.AmbientOcclusionRadiusScale=0.03
r.RefractionQuality=2
r.SSR.Quality=4
r.SSR.MaxRoughness=1
r.SSS.Scale=1
r.SSS.SampleSet=2
r.SSGI.Quality=4
r.DefaultFeature.AntiAliasing=2
r.PostProcessAAQuality=6
r.ScreenPercentage=100
r.TemporalAASamples=32
r.TemporalAACurrentFrameWeight=0.12
r.TemporalAAFilterSize=1.0
r.TemporalAACatmullRom=1
r.TemporalAAPauseCorrect=1
r.Color.Mid=0.40
r.Tonemapper.Quality=3
r.Tonemapper.Sharpen=0.33
r.TonemapperGamma=2.8
r.DepthOfFieldQuality=0
r.DefaultFeature.MotionBlur=0
r.SceneColorFringe.Max=0
r.SceneColorFringeQuality=0
r.MotionBlur.Max=0
r.MotionBlurQuality=0
r.Tonemapper.GrainQuantization=0

[/script/engine.userinterfacesettings]
ApplicationScale=0.75

[/script/engine.engine]
MinDesiredFrameRate=0


Save and closed.

It is also important to set the correct brightness, contrast, color and gamma on your screen. With Gamma, I took one with myself with 2.6 that darkens the background a little. To do this, try it out in the menu of your screen.

Another tip about performance:

Low fps fix: Go to your nvidia/amd graphics driver settings, program defined, biomutant.exe and disable vsync or set to fast sync.

Have fun.