ska-blocks plugin comes with controls for editing Tailwind configuration.
The controls can be accessed from ska-blocks Block Editor plugin item in the top right corner of the Block Editor screen, in the Tailwind tab:

When you change Tailwind configuration, all blocks and presets will automatically re-compile to ensure they are using the latest Tailwind configuration. For that reason, when you update the Tailwind configuration you may need to save changes twice in a row – once to apply the new configuration, second time to save all the re-compiled CSS.
When you go to change another post or a template then the blocks will also automatically re-compile if the configuration has changed in the meantime.
Tailwind theme
For extending the CSS-based Tailwind 4 theme you can add overrides to the Custom theme option. For reference you can toggle the “Show advanced options” checkbox and take a look at the Default theme option to see how the full configuration looks like.
It is generally best to avoid editing advanced options. When left at their default values, any updates, corrections, or fixes included in a plugin update can be applied automatically. However, if you modify these settings, then your changes will not be overwritten by future updates.
Typography and Theme colors options have a separate UI for easier editing.
Tailwind colors
Along with ska-blocks -> Tailwind -> Theme colors (which provide a UI for editing various common theme-related colors), there is an advanced setting Tailwind colors which contains all the default Tailwind colors.
The colors themselves are included in the Tailwind Default theme:
@theme default static {
@ska-blocks-tailwind-colors;
}
you may choose to omit them, replace them or move them to a separate @theme default inline reference { ... }
block if you wish for all the colors to not have a CSS variable defined on the front end.