This option is for Monorepos. More specifically, monorepo system that works with a single package.json at the root of the project.
You can run every subcommand of the keycloakify CLI tool from the root of your Keycloakify project using the --project (or -p) option. Example with the build command:
npx keycloakify build -p <path><path> would be typically something like packages/keycloak-theme
{% content-ref url="../keycloakify-in-my-codebase/as-a-subproject-of-your-monorepo/" %} as-a-subproject-of-your-monorepo {% endcontent-ref %}