If the seller has a No Returns on their listing and this is an item, asking to be returned for the reason... 'Doesn't Fit', then they can decline the request.
This is a difficult one, as a general sizing listing as ' large' can be interpreted widely, because one Brand can vary vastly to another.
The seller left themselves open here, for an item not as described case, which you can open if you feel that general description was wide ( no pun intended here! ) off the mark.
@danni-ava