This will search for Times New Roman font with 12 size and it will replace with font size 10.
Sub FindReplaceStyle()
With ActiveDocument.Content.Find
.ClearFormatting
With .Font
.Name = “Times New Roman”
Size = 12
End With
.Format = True
With .Replacement
.ClearFormatting
With .Font
.Size = 10
End With
End With
.Execute Forward:=True, Replace:=wdReplaceAll, _
FindText:=””, ReplaceWith:=””
End With
End Sub