https://wccftech.com/how-to/transfer-nintendo-switch-microsd-card-data/

So you’ve gotten yourself a new Nintendo Switch MicroSD card but you don’t want to loose the data on your current card. In this guide we’ll explain how to transfer data from one MicroSD card to another for use in the Switch.

Nintendo’s hybrid platform comes with 32GB of internal memory, but with games such as The Legend of Zelda: Breath of the Wild weighing in at more than 13GB and CDPR’s The Witcher 3 clocking in at roughly 30GB, most users are using the platform’s MicroSD port to expand the Switch’s storage capabilities.