Fluid style content "Menu of selected pages" subtitle // title

Question

TYPO3 v. 9.5.15

fluid_style_content and menu_pages

I'm using the TYPO3 Menu element "Pages - Menu of selected pages". As default Title is used. How can I change this so Subtitle is used ? Like this: subtitle // title

Before I could do something like this: tt_content.menu.20.default.1.ACT.stdWrap.field = subtitle // title