Hi Sheyad,
The theme doesn’t give you control of fonts, so you can install a plugin that helps you with that.
You can try using this one: https://www.ads-software.com/plugins/wp-google-fonts/
It is very easy to use: after you install and activate, you will see on the admin menu a “Google Fonts” item.
Once you click it, you can select a font from a dropdown, the styles that you need, and what elements you want to target.
Hope this helps you!