Available in Piebald Basic (Free)
Piebald allows you to customize the size of all text in the app to any size between 5 and 25 pixels, allowing for better resolution on smaller or larger screens.
You can customize both the interface font and the monospace font (used for code blocks, tool calls, etc.). You can choose any font installed on your system, or pick from 2,000+ Google Fonts.
To customize the font size and font family, go to Settings → Appearance and change Font Size, Font Family and Monospace Font Family.
Here’s a demo where we change the font size from the default 18px to 15px, and the font family from the default Figtree to Lustria (a Google Font):