Hi Rcwill,
Thank you for bringing this to our attention and taking an interest in the expandable memory and cloud storage capability of the Galaxy Z Fold3. Unfortunately, the device doesn't cater to a microSD card slot for additional storage. The internal memory capacity is up to 512GB only, and you need to sign in to your Google Account to access your Google Cloud Storage.
For more information, kindly visit the user manual on Pages 13 and 22:
https://downloadcenter.samsung.com/content/UM/202201/20220112001459078/SAM_F926_F711_EN_UM_OS12_010722_FINAL.pdf
Should you need more assistance, you may reach us via the following for immediate support:
1. Samsung Community: https://us.community.samsung.com/t5/Samsung-Community/ct-p/us
2. Facebook Messenger: http://m.me/samsungsupport
3. Twitter: https://twitter.com/messages/compose?recepient_ id=18768513
Reference Number: 1144300710
Thank you for choosing Samsung. Have a great day!
^Chrystel