Seems like the primary drop-down menu was not growing or expanding out when I use a larger font size. The links would stick outside of the dropdown. Here is the work-around I did, but is there a better way?
<!–
.main-navigation .main-nav ul ul li a { padding: 20px 70px 20px 30px; }
.main-navigation .main-nav ul ul li a { font-size: 18px; }
–>
Have you tried to adjust the padding using Customizer > Layout > Primary Navigation > Menu Item Width and font size in Customizer > Typography > Primary Navigation?