[nomesque]

You COULD probably do that in VBA. You'd need a loop which goes through the text searching for a 16pt-formatted character, highlights the whole word/paragraph, inserts a bookmark of the same name (replacing spaces with underscores, perhaps), then searches for text strings matching that bookmarked string, and adds a bookmark reference to each one of them.

Here's a start (because once I started talking about it, I had to see if it would actually work):

Sub SearchNBookmark()

Selection.Find.ClearFormatting
With Selection.Find
.Forward = True
.Wrap = wdFindContinue
.Format = True
.Font.Size = 16
End With
Selection.Find.Execute
Selection.Copy
With ActiveDocument.Bookmarks
.Add Range:=Selection.Range, Name:="Blah_blah_blah"
.DefaultSorting = wdSortByName
.ShowHidden = False
End With
With ActiveDocument.Bookmarks
.DefaultSorting = wdSortByLocation
.ShowHidden = False
End With
Selection.Find.ClearFormatting
With Selection.Find
.Text = "Blah blah blah"
.Forward = True
.Wrap = wdFindContinue
.Format = False
End With
Selection.Find.Execute
Selection.InsertCrossReference ReferenceType:="Bookmark", ReferenceKind:= _
wdContentText, ReferenceItem:="Blah_blah_blah", InsertAsHyperlink:=True, _
IncludePosition:=False, SeparateNumbers:=False, SeparatorString:=" "
End Sub