Is the one you’ve seen in store fibre filled? The one we bought (Blakely, I think it’s actually been discontinued now) was available in foam and in fibre.
After owning a fibre filled sofa that was like a sack of spuds after 6 months, we went for foam this time.
They do have a mixture of them in store to sit on - at least they did at the store near us. If you’ve said it’s very soft I’d be surprised if the one you’ve sat on is foam-filled. They usually feel relatively firm and supportive, but still comfortable!