Thanks for reaching out with your question. When it comes to larger font sizes in Atticus, I understand the need for flexibility for certain projects, however, Atticus is a template-based program designed to align with industry standards needed for most authors, so it does have some limitations.
Here’s what’s possible in terms of font sizing within Atticus:
Body fonts: Go up to 18pt.
Subheadings: Can be set up to 2x your body font size in the Theme Settings (maxing out at 36pt).
Chapter Titles: Can go up to 54pt.
If you need fonts larger than 54pt (e.g., for headings or illustrations), the best approach within Atticus would be to create those pages in another program, save them as images (PNG or JPEG), and import them into Atticus as full-page images. This works well for print books but keep in mind that ePubs typically require adaptable formatting, which images can’t provide.