Given that patios can get damaged in time, not many retailers accept returns in this department. Home Depot, for example, sticks to a 30-days return policy when it comes to furniture of all kinds. You can take back a patio set to Wayfair in 30 days, as well, conditioned it is brought in its original packaging.
What does Costco do? It accepts patio set returns even if you bought the set one year ago and the elements of nature have not been kind to the chairs or umbrella.