Can I change the typeface and size of the headings?

Yes. The font is chosen at the template/proposal level, and each heading’s size and level are adjusted one by one.

1. 1Heading font: in the editor, “Settings” → “Design and color” (or in a custom template on the Business plan).
2. 2Size and level of a specific heading: click the heading and use the floating bar (H1/H2/H3 for the SEO level and the size slider).

Consejo: The H1/H2/H3 level doesn’t change the look, it only helps SEO. You set the visual size with the slider.