Some online shops offer the option of having a return label printed at a Post Office or Post Point. Online shops mostly communicate this as follows:

• With the return label you receive by email.
  In the email it may be stated that you can have it printed at a Post Office or Post Point.
• On the returns page of the online shop.
  You can usually read here how to request or download a return label. And whether you can have it printed at a Post Office or Post Point.

If you cannot find this information, the online shop probably does not offer this option. Contact the sender if you want to know for sure.