Font Resizing as a widget

Hello fellas,

I am using axure for 2 months and teached myself via YouTube. Currently I am working on a Prototype and wanted to add a feature, where you can open a dynamic menu and click on a button [font size +] or [font size -]. Combining both features inside a single button, would be much nicer, like [Font size] -> [+/-]. These Buttons should resize the text of all paragraphs inside of a page. Ideally this change takes effect on all pages.
Now I have no clue if I should use the dynamic panel and work on cases, but I haven’t found an option where you can set the size on click of all paragraphs.
Any idea on how to achieve this without the need to select all paragraph?