Go to Theme settings > Typography
You can adjust your Typography in 2 ways.
You this way you can use hundreds of available Google font. However you can’t use Special font
Font text(by shopify)
Result: All the text on the site is POPPINS
Result: All the texts on the site (except the Header) are changed after you changed the font
Text transform main header
To change font here:
Use Custom font? you can use Fontify App from App store to upload to your site any special fonts
Hope you success!!