From my knowledge accessories are not what Samsung give future updates on when coming to releasing information.
They just tend to show up on the Samsung Online Store. They also offer a limited option for each particular phone model.
May I assume you've looked on Amazon for a suitable case.
These look nice mobilefun.co.uk/samsung/galaxy-a21s/cases/wallet-cases.
Current Phone ~Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+ Samsung One Ui 3.1/ Android 11.