I just plug in an external SSD formatted with exFAT via the USB-C port and manually copy folders (Documents, DCIM, Downloads, etc.) to it in the Files app. Aft

I just plug in an external SSD formatted with exFAT via the USB-C port and manually copy folders (Documents, DCIM, Downloads, etc.) to it in the Files app. After dismounting it in the Settings app (Advanced menu), I plug it into my computer and copy any files over I want to store there too (e.g., Pictures).