additional class on thank you page?

in the output of this action in the plugin:
add_action('woocommerce_thankyou_payinstore', array($this, 'thankyou_page'));

It only wraps the text in p tags as such:

public function thankyou_page() {
    if ($this->instructions) {
       echo wpautop(wptexturize($this->instructions));
    }
}

Making it impossible to reliably target it with CSS style changes.

Would you be able to wrap it in a div that you apply a plugin specific class to it like this?

echo '<div class="woocommerce-payinstore-thankyou-instruction">' . wpautop(wptexturize($this->instructions)) . '</div>;