We can easily apply a custom font to a specific element by checking the Specific Element option and enter the element class or ID in the input box.
We can also use the Collapsible stack for this purpose:
1 - drop a Collapsible stack to the page
2 - type a name in the Custom Class field of Collapsible, any name for example:
3- On the Font File stack check the *Specific Element* option and enter the same name preceded by a dot, like so:
That's all. You just gave the Collapsible stack container a custom class name and used this same class to trigger a font from File Font stack.