font-family name is defined in the source/scss/variables.scss files. If you want to change the font then change the font-family form here. And give your font link to the source/scss/typography.scss files or in html head tag.
In typography.scss files, you can customize the font-size, font-weight, and line-height of your texts. You can get more font-face form here.
// font links from typography.scss file
@import url('https://fonts.googleapis.com/css?family=Roboto:wght@100&display=swap');
<!-- font links from head tag in html file -->
<link href="https://fonts.googleapis.com/css2?family=Roboto:wght@100&display=swap" rel="stylesheet">
// Font Variables from variables.scss file
$primary-font: 'Roboto', sans-serif;