Is it possible to switch templates in ArcGIS Experience Builder?

No, it is not possible to switch templates in ArcGIS Experience Builder. When creating a new experience, after selecting a template, the choice becomes irreversible. Templates come with default configurations and elements, and attempting to switch templates between editing affects the layout of the data. As a workaround, remove or add elements to the experience to suit the needs of the experience. To be able to make edits to the template, toggle Lock layout off. This setting is located on the header of the ArcGIS Experience Builder editing page. Alternatively, create a new experience by either selecting a more suitable template or creating one from scratch through a blank template. Refer to ArcGIS Experience Builder: Create your first web experience for more information.