There’s an ongoing discussion around allowing users to change font size via the formatting toolbar. Some concerns were raised about preserving consistency across documents and making font size a site-level theme rather than a per-block option. A suggestion was made to use headings for emphasis and smaller fonts for quotes or citations via a dedicated block type.
Consensus:
Font size customization could live in site theming.
Formatting toolbar font size is low priority.
Use cases like quote formatting may be better addressed with custom blocks.