Block supports require coordination between block.json declarations, WordPress core theme.json defaults, and active theme theme.json settings. Each level can override the previous one, controlling which features actually appear in the editor.
WordPress ships with permissive defaults in wp-includes theme.json, enabling most block support features. Active themes can restrict or enhance these settings through their own theme.json configuration.
Understanding this hierarchy prevents confusion when block supports don’t appear as expected. Always check theme.json settings if declared supports aren’t showing in the editor interface.