Headings Typography

Appearance → Customize→ Fonts Plugin → Basic Settings

The 'Headings Typography' control doesn't have a font size control as it modifies all heading types.

Clicking the blue icon to the left of the ‘Font Family’ will reveal additional typography controls: Font weight, style, size, color and line-height settings.

If your changes aren’t taking effect, you may need to enable the ‘Force Styles’ setting.

The following CSS selectors are targeted:

#site-title, .site-title, #site-title a, .site-title a, .entry-title, .entry-title a, h1, h2, h3, h4, h5, h6, .widget-title