Use the `size` attribute to change the font size of the navigation item:

- `sm`: Used for 3rd level navigation
- `base` (default)
- `lg`: Used for 2nd level navigation

```html
<div class="flex flex-col gap-6">
  <sd-navigation-item size="sm">Small</sd-navigation-item>
  <sd-navigation-item>Default</sd-navigation-item>
  <sd-navigation-item size="lg">Large</sd-navigation-item>
</div>
```