The Size property returns or specifies the font size for a text range..
Examples:
The following VBA example sets the font of the paragraph to 24-point Arial.
Sub Test()
Dim d As Document
Dim s As Shape
Dim t As Text
Set d = CreateDocument
Set s = d.ActiveLayer.CreateParagraphText(3, 3, 5, 5, "This is an example.")
Set t = s.Text
t.Story.Font = "Arial"
t.Story.Size = 24
End Sub