Hi

Thanks for contacting us. Could you please give me your site URL? So that I can check.

-Regards.

targetingsmart.com

Hi Ed.

For example by: Helix Template Options > Typography > Custom - where you have to use that class name:

.offcanvas-menu .offcanvas-inner .sp-module ul > li a, .offcanvas-menu .offcanvas-inner .sp-module ul > li ul li a

and select font + font-size

OR

By Custom CSS (Template Options > Custom Code > Custom CSS)

.offcanvas-menu .offcanvas-inner .sp-module ul > li a, 
.offcanvas-menu .offcanvas-inner .sp-module ul > li span {
  font-size: 1.4rem;
  font-weight: bold;
}

As I saw above CSS was used, probably by you or previous webmaster.

But for submenu items in Mobile Menu, you can use also that:

.offcanvas-menu .offcanvas-inner .sp-module ul > li ul li a 
{font-size: 1.1rem; }

To get that view/size