Can Kadence Row layout be used as the gutenberg default block?

Hello Nick,

Thank you for reaching out to us.

There is no built-in option to do that but you may use a code snippet to use the Row Layout block every time you add a new post. For code reference, you may refer to this thread answer.

You can use the Code Snippets plugin and use this code:

function use_row_layout_first() {
    $post_type_object = get_post_type_object( 'post' );
    $post_type_object->template = array(
        array( 'kadence/rowlayout' ),
    );
}
add_action( 'init', 'use_row_layout_first' );

Hope this helps.

Regards,
Karla