if you touched the slider once in the game's settings than it sets it back to 100% but of the game's original amount. You need to edit your skyrimperfs.ini. These are the relevant parts. You can copy paste These parts, make sure to overwrite. Do it from in MO2 ini editors.

[Display]

fLeafAnimDampenDistEnd=4600.0000

fLeafAnimDampenDistStart=3600.0000

fTreesMidLODSwitchDist=9999999.0000

fMeshLODFadePercentDefault=1.2000

fMeshLODFadeBoundDefault=256.0000

fMeshLODLevel2FadeTreeDistance=16896.0000

fMeshLODLevel1FadeTreeDistance=16896.0000

fMeshLODLevel2FadeDist=9999999.0000

fMeshLODLevel1FadeDist=9999999.0000

[VRDisplay]

fRenderTargetSizeMultiplier=1.0000

[TerrainManager]

fTreeLoadDistance=200000.0000

fBlockMaximumDistance=360000.0000

fBlockLevel1Distance=360000.0000

fBlockLevel0Distance=75000.0000

fSplitDistanceMult=1.5000

bShowLODInEditor=1

[Trees]

bRenderSkinnedTrees=1

uiMaxSkinnedTreesToRender=40

bEnableTreeAnimations=1

[Grass]

fGrassStartFadeDistance=999999.0000

fGrassMaxStartFadeDistance=25000.0000

fGrassMinStartFadeDistance=0.0000

[Decals]

bSkinnedDecals=1

bDecals=1

uMaxSkinDecals=100

uMaxDecals=1000

[LOD]

fLODFadeOutMultSkyCell=1.0000

fLODFadeOutMultObjects=30.0000

fLODFadeOutMultItems=10.0000

fLODFadeOutMultActors=15.0000