enum sets

I am wondering how useful would be to have enum sets.
Let´s say you have a function that accepts only monospaced fonts.Then you can use enum monospaced_font_type. Or a switch case where you need to check all and only monospaced_font_type.
But at same type you can store at same object monospaced_font_type or font_type.
enum font_type
{
     enum monospaced_font_type
     {
         CASCADIA_FONT,
     },
     ARIAL_FONT
};
This could be arranged in any way.