We have a local store near me, and Uniqlo used to take returns. It made ordering online really easy. But about three years ago, the policy changed, and returns in store were not allowed for online orders. If they had your item in stock at the store and you wanted to exchange what you ordered for another size or color, that was allowed. Unfortunately, our store was a very small one, so only the basics were stocked.
I'm a lot more careful with my ordering these days because of Uniqlo's policy. When we travel, if our destination(s) has a large Uniqlo, I'll go in and check it out. Some of my best Uniqlo scores, including collabs, have been in Berlin, Hamburg, Victoria, BC, and NYC.