잘은 모르지만 아래처럼 응용하시면 되실듯

Option Explicit

Sub Test()
    Dim rng     As Range
    Dim strA    As String
    Dim i       As Integer
    Dim f       As Integer
    Dim n       As Integer
   
    Set rng = Range("A1:A3")
    For i = 1 To rng.Rows.Count
        f = InStr(rng(i, 1).Value, "!#")
        n = InStr(rng(i, 1).Value, "!%") - f + 2
        With rng(i, 1).Characters(f, n).Font
            .Size = 10
            .Bold = True
        End With
    Next
End Sub