// This is like the woocommerce function
function load_content_demo( $original_template ) {
        if ( is_singular( 'demo' ) && in_the_loop() ) {
            return wpbp_get_template_part( 'plugin-name-folder', 'content', 'demo', false, array() ); // The last parameter is for arguments to pass to the template but is not mandatory
        } else {
            return $original_template;
        }
}
add_filter( 'template_include', 'load_content_demo' );

// This is an extended version that search for folder with names based on locales like it_IT
$get_template_email = wpbp_get_template_part( 'plugin-name-folder' , 'header', 'prefix' );