Which system or platform are you using? Font-size settings vary by where your site or document is built. Below are quick instructions for the most common places; pick the one that matches your setup.

1. WordPress (block editor/Gutenberg)

• Site-wide: Appearance → Customize → Typography or Global Styles. Change Base font size and heading sizes.

• Theme settings: Appearance → Customize → (Theme Options or Typography). Some themes provide separate controls for H1–H6, body, nav, and footer.

• Individual blocks/pages: Select a block in the editor → Block settings on the right → Typography or Text size. You can set predefined sizes or enter a custom size (px, em).

2. WordPress (Classic editor or page builders)

• Classic editor: Use theme styles/CSS or a plugin like Easy Google Fonts to control sizes.

• Elementor: Site Settings → Typography for global sizes; or select any widget → Style → Typography to change size per widget.

• WPBakery/Beaver Builder: Open element settings → Typography/Text options.

3. Shopify

• Online Store → Themes → Customize → Theme settings → Typography. Choose fonts and sizes for headings, body, buttons, etc.

• For specific section tweaks, open the section in the customizer and check its typography options.

• For custom changes, edit theme CSS (Assets/theme.css or base.css).

4. Squarespace

• Design → Site Styles. Click text (heading/body) in the preview or use the text options to adjust H1–H6 and body sizes.

• For finer control, use Custom CSS (Design → Custom CSS).

5. Wix

• Site Editor: Click any text element → Edit Text → Text Settings/Design to change font size. Use Site Design → Text to set global text styles.

• Editor X: Use the Style Panel to set responsive font sizes for text elements and theme text.

6. HTML/CSS (custom site)

• Edit your CSS. Common places:

  • body { font-size: 16px; } (base size)

  • h1, h2, h3, h4, h5, h6 { font-size: ...; }

  • .site-header, .nav, .footer, .hero { font-size: ...; }

• Use relative units (rem, em) for responsive scaling:

  • html { font-size: 100%; } /* 1rem = 16px */

  • h1 { font-size: 2.5rem; }

• For responsive control, use media queries:

  • @media (max-width: 768px) { h1 { font-size: 2rem; } }

7. Adobe XD / Figma

• Select text layer → Properties panel → Font size. Use Text Styles / Typography system for consistent sizes across the design.

8. Microsoft Word / Google Docs

• Select the text or style (Normal, Heading 1, etc.) → Format → Paragraph/Styles → Font size to change styles globally.

9. Mobile Apps (iOS/Android)

• iOS: Adjust UIFont or use Dynamic Type settings in the app. Change text styles in Interface Builder or code.

• Android: Use styles.xml (textAppearance) or dimension resources for text sizes.

If you tell me which platform, theme, or tool you're using (and whether you want global or per-section changes), I’ll give step-by-step instructions tailored to it and, if needed,