Turacos theme used popular plugin “Google Typography” for Typography options. For more information about this plugin please visit here.
Step:1
For changing typography first you have to go Appearance -> Typography.

Step:2
Click Add New button for adding your desired font-family, font-weight, font-size, color & CSS selectors like as h1, h2, …..h6, p, li, a, span, body etc. also, you are able to add classes & IDs.

Step:3
After done above click save

N.B. You can’t not modify Turacos custom CSS for this.