Hello,
You can do this using the Child Theme.
Do you have the font in web files?
In your Child Theme there’s a folder called ‘assets’, in which you have to create a new folder called ‘fonts’. Then upload all the font’s files that you have into the ‘fonts’ folder.
Then you need to enter the font’s code into the assets/css/style.css/ file.
This way you’ve added the font to the theme.