: Go to Settings > [Your Name] > iCloud > Manage Account Storage > Change Storage Plan .
It is important to note that the Go to product viewer dialog for this item.
has a fixed amount of internal storage that cannot be physically upgraded or expanded after purchase. While you cannot increase the phone's native capacity, you can gain more space by using cloud storage services, external hardware, or manual storage management. Cloud Storage Options
If you prefer physical storage, you can use specialized accessories that plug directly into the iPhone 6's Lightning port.
: Platforms like Google Drive or Dropbox can also be used to store large files and backups. External Hardware Solutions