Apple One Plans are too limited

If you have Family Sharing set up, you can share 200 GB or 2 TB of iCloud+ storage with your family. You can cancel your Apple One subscription, then upgrade to iCloud+. If you already have Family Sharing set up, your iCloud+ storage should be shared with your family. When you cancel Apple One, you'll lose access to your other Apple services, like Apple Music and Apple TV+.

Set up Family Sharing - Apple Support

Apple One Family is $19.99/month and includes 200 GB of iCloud+ Storage. If you want to keep the same amount of storage, you can upgrade to Apple One Premier and pay the same price that you would be paying for Apple One Family and an additional 2 TB of iCloud+ storage.