add_action( 'woocommerce_review_order_before_submit', 'add_consent_checkbox', 9 );
function add_consent_checkbox() {
woocommerce_form_field( 'consent_policy', array(
'type' => 'checkbox',
'class' => array('form-row privacy'),
'label_class' => array('woocommerce-form__label woocommerce-form__label-for-checkbox checkbox'),
'input_class' => array('woocommerce-form__input woocommerce-form__input-checkbox input-checkbox'),
'required' => false,
'label' => 'Please send me your special offers and update emails. <a href="urlforpolicypage">Privacy Policy.</a>',
));
}

add_action('woocommerce_checkout_update_order_meta', 'customise_checkout_field_update_order_meta');
 function customise_checkout_field_update_order_meta($order_id)
{
	if (!empty($_POST['consent_policy'])) {
		update_post_meta($order_id, 'Consent Accept', sanitize_text_field($_POST['consent_policy']));
	}
}