Fonts are set in the Site Settings → Fonts and Colors. Also you can set global font settings for headings and body text (saturation, size, color) which will be applied globally to all blocks on all pages of the website.
To customize the site fonts, go to Site Settings → Fonts and Colors.
You will see a font gallery. You can navigate through it and assign a font to the website by clicking the "Select" button. The font will be assigned to the website heading and body text.
If you want to use a third-party font or use different fonts for header and text, click the Advanced Settings button.
You can choose different fonts for the Heading Font Family Name and the Body Text Font Family Name in the Basic Fonts tab.
The Google Fonts, Adobe Fonts, and Your Own Font tabs allow you to use a font from an external source. See the detailed articles below to read more about these options.
Setting the fonts of the website headings and text
Fonts and Colors tab contains the default size, saturation, and color settings for website titles and text. These settings are set globally for all blocks on the site (except Zero Blocks), unless other font settings are hardwired into them.
You can specify the font parameters in the block settings → Typography or select the text in the editor and change its parameters using the top panel.
Setting font options via the text settings panel in the editor
Set the parameters of text elements through the block settings → Typography
Font loading settings
By default, the website text is shown after the font file is loaded, this may happen with a certain delay depending on the speed of the connection.
You can set the system fallback font to show when the website loads in Site Settings → Fonts and Colors → Advanced. So that the text will be shown immediately, but first in the fallback font, and then in the font you selected. This may cause short flickering of text and resizing of text elements, so use this setting only if you are sure that it makes your website look better at loading.