Espresso is a basic drink of the coffee. If you add a tip of frothed milk on top espresso with half packet sugar may taste good to me. If you want so fancy flavour, you may add flavour syrup like vanilla, hazelnut, irish cream, caramel etc. I saw few time where they served espresso not in proper way as
not up to the standard of espresso. I only drink the 1 i make but it was several years ago.