Landscape orientation for invoice

Is there a way to change the page orientation for the generated PDF? I would like to set it to landscape mode but could not find any easy way.

If there is no direct way currently present, here is what I propose:
In wcpdf-functions.php we have following function:

function wcpdf_get_pdf_maker( $html, $settings = array() ) {
	if ( ! class_exists( '\\WPO\\WC\\PDF_Invoices\\PDF_Maker' ) ) {
		include_once( WPO_WCPDF()->plugin_path() . '/includes/class-wcpdf-pdf-maker.php' );
	}
	$class = apply_filters( 'wpo_wcpdf_pdf_maker', '\\WPO\\WC\\PDF_Invoices\\PDF_Maker' );
	return new $class( $html, $settings );
}

In this function just before returning the PDF_Maker object, apply filter wpo_wcpdf_pdf_maker_settings which will allow modifications to $settings array.

Later on you can add the setting in UI as well.