"Glyph Variants not available" in Pages for Trattatello, how do I access them?

I am trying to fiddle around with the glyph variants in Trattatello for one of the titles in a Pages document, but I cannot get them to show up in the Typography menu when I highlight the characters I want to switch (i.e., I press cmd+T, select Trattatello, select Typography, & highlight the text to be changed). Instead, I just get the message "Glyph Variants not available". Does anyone know if there's a step I'm missing or something is wrong? I'm on the latest version of macOS Sonoma. Any help would be hugely appreciated.