You would need to implement a loop, to process point sizes starting at 1 and ending at 10, in 0.5pt increments. For example:
Code:
Dim i as long
With Selection.Range.Find
.Forward = True
.Replacement.Font.Size = 12
.Replacement.Font.Name = "Arial
.Wrap = wdFindStop
For i = 2 to 20
.Font.Size = i / 2
.Execute Replace:=wdReplaceAll
Next
End With