public ViewEntityInterface::addDisplay($plugin_id = 'page', $title = NULL, $id = NULL)
Adds a new display handler to the view, automatically creating an ID.
Parameters
string $plugin_id: (optional) The plugin type from the Views plugin annotation. Defaults to 'page'.
string $title: (optional) The title of the display. Defaults to NULL.
string $id: (optional) The ID to use, e.g., 'default', 'page_1', 'block_2'. Defaults to NULL.
Return value
string|bool The key to the display in $view->disp