To change the Font Size in the modal, put this CSS in the plugin Settings → Custom CSS field:

For member name:

#sptp-3497 .sptp-popup-content .sptp-member-name h2 {
font-size: 28px !important;
}

For a member job title or position:

#sptp-3497 .sptp-popup-content .sptp-member-profession h4 {
font-size: 22px !important;
}


You can change the font size as you wish.

Note: Replace the shortcode ID with yours from the CSS. In this case, it is #sptp-3497.