To change both headings and body fonts, add the following CSS code inside Customizer > Additional CSS:
body,
.entry-content,
.entry-content p,
.entry-content ol,
.entry-content ul,
.widget_text p,
.widget_text ol,
.widget_text ul,
.widget-content .rssSummary,
.comment-content p,
.entry-content .wp-block-latest-posts__post-excerpt,
.entry-content .wp-block-latest-posts__post-full-content,
.has-drop-cap:not(:focus):first-letter,
h1,
h2,
h3,
h4,
h5,
h6,
.entry-content h1,
.entry-content h2,
.entry-content h3,
.entry-content h4,
.entry-content h5,
.entry-content h6,
.faux-heading,
.site-title,
.pagination-single a,
ul.primary-menu,
ul.modal-menu,
.intro-text,
input,
textarea,
select,
button,
.button,
.faux-button,
.wp-block-button__link,
.wp-block-file__button,
.entry-content .wp-block-file,
.primary-menu li.menu-button>a,
.entry-content .wp-block-pullquote,
.entry-content .wp-block-quote.is-style-large,
.entry-content .wp-block-quote.is-style-tw-large-icon,
.entry-content cite,
.entry-content figcaption,
.wp-caption-text,
.entry-content .wp-caption-text,
.widget-content cite,
.widget-content figcaption,
.widget-content .wp-caption-text,
.entry-categories,
.post-meta,
.comment-meta,
.comment-footer-meta,
.author-bio,
.comment-respond p.comment-notes,
.comment-respond p.logged-in-as,
.entry-content .wp-block-archives,
.entry-content .wp-block-categories,
.entry-content .wp-block-latest-posts,
.entry-content .wp-block-latest-comments,
p.comment-awaiting-moderation,
.pagination,
#site-footer,
.widget:not(.widget-text),
.footer-menu,
label,
.toggle .toggle-text {
font-family: "Century Gothic", CenturyGothic, AppleGothic, sans-serif;
}
That’s a lot of code, but that’s how the Twenty Twenty theme is coded.
Have a nice day.