Hi @lalz,
The theme is not built with any page builder. It makes a good use of the capabilities of the WordPress Customizer and it is very easy to create pages, sections and customize all pre-existing components.
We have plan to make Cera compatible with Elementor in a future update. But you can still install Elementor (“Grimlock for Elementor” plugin will also be necessary) and build your new pages with the components offered by our plugins and the theme (widgets) and simply mix them (or not) with Elementor widgets.
On the other hand, you will not be able to edit existing pages because they have not been created with Elementor.
Hope this help.
Regards,