Private Sub Worksheet_SelectionChange(ByVal Target As Range) 
  If Target.Count >  1  Then Exit Sub
   If Target.Column =  4  Then
       Target.Columns.ColumnWidth =  20 
   Else
       Columns( 4 ).ColumnWidth =  5 
   End If 
End Sub 

Private Sub Worksheet_SelectionChange(ByVal Target As Range) 
  If Target.Address  = "$A$2" Then 
    ActiveWindow.Zoom =  120  
  Else 
    ActiveWindow.Zoom =  100  
  End If 
End Sub 

Private Sub Worksheet_SelectionChange(ByVal Target As Range) 
  If Target.Cells.Count >  1  Then Exit Sub
  If Intersect(Target, Range("A1,B3,D9")) Is Nothing Then 
    ActiveWindow.Zoom =  100  
  Else 
    ActiveWindow.Zoom =  120  
  End If 
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)
  Dim lZoom As Long
  Dim lZoomDV As Long
  Dim lDVType As Long
  lZoom =  100 
  lZoomDV =  120 
  lDVType =  0 

  Application.EnableEvents = False
  On Error Resume Next
  lDVType = Target.Validation.Type
  
    On Error GoTo errHandler
    If lDVType <>  3  Then
      With ActiveWindow
        If .Zoom <> lZoom Then
          .Zoom = lZoom
        End If
      End With
    Else
      With ActiveWindow
        If .Zoom <> lZoomDV Then
          .Zoom = lZoomDV
        End If
      End With
    End If

exitHandler:
  Application.EnableEvents = True
  Exit Sub
errHandler:
  GoTo exitHandler
End Sub