In general, you can customize the template of how the printouts are generated - you can look here for details.
In particular, you can also choose whichever web-safe font family for the printouts of the templates. You can find which are the best web-safe fonts here.
As for a custom font, you can add it and it will show as should when printing and in the PDF attachment of the email. However, the font will not be displayed correctly in the HTML body of the email. This happens because the recipients will not have the font installed on their devices.
Do you need more assistance? Reach out to us!