The following code scales the rectangle to the both sides.

I want to scale the rectangle to the one side.

In other words I want to scale the rectangle from left to right.

    Sub Macro1()
    
    'Delete all slides
    For i = ActivePresentation.Slides.Count To 1 Step -1
        ActivePresentation.Slides(i).Delete
    Next i
    
    'Add a blank slide
    ActivePresentation.Slides.Add 1, ppLayoutBlank
    
    'Add a Rectangle
    With ActivePresentation.Slides(1).Shapes.AddShape(Type:=msoShapeRectangle, Left:=100, Top:=100, Width:=200, Height:=50)
        .Name = "myRectangle"
    End With
    
    'Add a Scale effect to the myRectangle
    With ActivePresentation.Slides(1).TimeLine.MainSequence.AddEffect(Shape:=ActivePresentation.Slides(1).Shapes("myRectangle"), EffectId:=msoAnimEffectCustom, Trigger:=msoAnimTriggerAfterPrevious)
        With .Behaviors.Add(msoAnimTypeScale)
            'Starting size
            .ScaleEffect.FromX = 100
            .ScaleEffect.FromY = 100
            'Ending size
            .ScaleEffect.ToX = 200
            .ScaleEffect.ToY = 100
        End With
        .Timing.SmoothStart = msoTrue
        .Timing.SmoothEnd = msoTrue
        .Timing.Duration = 5
    End With
    
    End Sub

Thanks in advance. Thanks in advance.