You just need the flexible fare for refund. Fully flexible fares don't have advance purchase requirements and basically can be changed to most any time without additional fare charges. While there will often be fare differences if you wish to change a cheaper flexible fare to a different flight on a route close to flight time (but it still remains refundable). This is the text to look for refundable fares in Penalties section of fare rules. It's easier to read fare rules on ITA Matrix which is free (or Expert Flyer which has fee). Perhaps not the most straightforward, but pretty much all airlines use the same basic "Cancellations permitted" text for refundable fares. It is what it is.



This is what the section says on non-refundable fares which is more obvious.