Use Excel VBA to change font color of word in Word document

Maybe :

Sub Test()
  Const wdReplaceNone = 0
  Const wdReplaceOne = 1
  Const wdReplaceAll = 2
  Dim objApp As Object, objDoc As Object

  Set objApp = CreateObject("Word.Application")
      Set objDoc = objApp.Documents.Open(ThisWorkbook.Path & "\MyWordDoc.doc")
          With objDoc.Content.Find
             .ClearFormatting
             With .Replacement
                .ClearFormatting
                .Font.Color = vbRed
             End With
            '.Execute FindText:="*", ReplaceWith:="*", Format:=True, Replace:=wdReplaceAll
            .Execute FindText:="*", Format:=True, Replace:=wdReplaceAll
          End With
      objDoc.Close True
  objApp.Quit
End Sub