At the time of writing, the most storage available on the iPad mini 6th generation is 256GB. Moving up to 512GB would be the logical step, especially if the baseline storage moves to 128GB.
Where to buy the iPad mini 6th gen? You can buy one from Apple and a number of other retailers (either outright or with a network provider), details of which you will find below. For a while part ...
Amazon is selling every single version of Apple's 2021-released iPad mini 6 at an unprecedented $150 discount for Prime members only for a limited time.