AnimationSettings.DimColor (PowerPoint)

Returns or sets a ColorFormat object that represents the color of the specified shape after it is been built.

If you don't get the effect you expect, check your other build settings. You won't see the effect of the DimColor property unless the TextLevelEffect property of the AnimationSettings object is set to something other than ppAnimateLevelNone, the AfterEffect property is set to ppAfterEffectDim, and the Animate property is set to True. In addition, if the specified shape is the only item or the last item to be built on the slide, the shape won't be dimmed. To change the build order of the shapes on a slide, use the AnimationOrder property.

Dim cftDimColor As ColorFormat
Set cftDimColor = ActivePresentation.Slides(2).Shapes(2).AnimationSettings.DimColor