To customize theme typography navigate to Appearance > Customize > Typography to start customizing the theme Typography.
Here you can control Typography options such as Font Family, Font Weight, Font Size, Line Height, Font Color.

- Headings & Body
Customize H1-H6 headings and body typography in this section. - Main Navigation
Customize theme Main Navigation typography in this section. - Widget Title
Customize theme widget title typography in this section. - Page Heading
Customize theme page heading typography in this section.