You can upload new fonts by following these steps:
1. Navigate to Campaign Editor
2. Switch to HTML & CSS
3. Click on Files and Upload Fonts
4. Create new font and upload woff, woff2
5. Go back to Editor and click on Configuration
6. Navigate to ‘Campaign font primary’ and ‘Campaign font secondary’
7. In the dropdown window, find the font that you’d like to set up, choose it, and save changes