I’m not sure it is. IME plaza lounges are typically at the bottom end of the scale (admittedly I haven't visited the star locations in Asia). Almost zero presence in North or South America (except Canada which is currently off limits) and not much in Africa which is a continent where lounges are essential! Asia is actually the one place I don't need this option, with wonderful SQ, Cathay, Qantas and others.

in any case it appears this does not apply to Amex Plat, which has a separate deal (according to Gleff)