This depends on what payment gateway that you have installed on the site, and if it allows for auto refunds through it. If you can, could you please share a copy of your site’s System Status? You can find it via WooCommerce > Status. Select “Get system report” and then “Copy for support”. Once you’ve done that, paste it here in your response.
This will allow us to see what payment gateway plugins other than the Checkout gateway which might be on the site. Also, it is recommended to update/upgrade your plugin to PayPal Payments, found here if you have not already done so. The link will have update instructions at the top of it.