Hey Scott,
thank you for choosing Bento! I will reply here as well as by email just in case 😉
There’s no Customizer control for the submenu font size at the moment, but you can change it by adding the following snippet to the “Additional CSS” tab of the “Appearance – Customize” admin section:
.primary-menu .sub-menu li a { font-size: 20px; }
We will consider adding a separate admin setting for the submenu font size in the next versions of the theme.
Sincerely,
Andrii / Satori Studio