You can set the number of days till when the return order or product is eligible. Once the date is expired, customer will not be able to initiate return or use the returns button in the customer order info page.
You can set when the return order button shown be displayed depending on the current order status of the order. For example you will not want to show returns button when the order is in pending status.
Customer can cancel the order themselves
You can set on what all order status a customer can cancel his order. For example you can set a customer can only cancel order only if the order status is in pending, processing or processed status.
You can set the number of days till when a customer can cancel his order. Once the date is passed, customer will not be able to cancel his order.
When the customer cancels his order, he will receive the order status update email as per opencart settings.
All of the features are only for logged in customers.