How to free up iPhone storage when iCloud Photos is enabled?

First you need to make sure you have Optimized Photos enabled in your Photos Settings.

This will offload the full resolution photos to iCloud and smaller versions will remain on your device for viewing/browsing in Photos. When you need to edit, zoom or print the photo, then the full resolution photo will need to be downloaded from iCloud and stored on your device. After a while when no longer needing that full resolution photo, the file size of the photo stored on your device will be reduced with the lower quality version taking up less space until needed again.

There is no such thing as your entire Photo Library being offloaded to iCloud even when using Optimized Storage, your are still going to need storage space on your phone to view those smaller thumbnail versions in the Photos app. Also the offloading and downloading of the photos to iCloud is all done automatically and you don't have any manual control over the process.

If you are still running out of storage on your iPhone, you will need to look elsewhere for what is taking up that space.

Check iPhone Storage

In any case, the storage on your iPhone is limited to the size that it was when purchased, which is why you can buy them in many different sizes. If you require a lot of data, then buying the device with the lowest amount of storage space may soon become a problem. Using iCloud is not intended to be a way to extend the storage on a device. It is a syncing service not an external storage solution like you would find with a service such as DropBox or OneDrive.

Note there's different kinds of "storage". Click on this link to discover what's the difference between device and iCloud storage, ways to manage your space, and upgrading to iCloud+ if you need more --> https://support.apple.com/HT206504

Take-away:

1. Storage on a device itself is fixed and cannot be upgraded except at the time of purchase. If you want that then you have to change your present device for one with more capacity.

2. iCloud storage is on Apple's main computers. It is not a like a normal storage hard drive but by using optimization settings on your device it can help free up device storage. iCloud storage can lessen the amount of storage used on your iPhone but it's basic design is to provide a syncing and backup service for your data with all your data existing in both iCloud and on your iPhone too. Lesser used items and larger file versions can be stored in ICloud and you can get access while connected to the Internet. It does not turn a 64 GB storage device into a 64 (or whatever) + 50GB/200GB/2TB device but if you have a lot of things that aren't being used much, or you don't mind only having lesser quality photos on your device, it can free up extra space so you can make the best of the GB you do have on the device itself.

If you have upgraded iCloud storage and are seeing a message on your device that storage is full then it is possible you are not making the best use of iCloud storage and need to use optimization features. If you do have optimization activated then it is possible you are exceeding your device's needs in terms of on-device storage and you need to buy a device with more storage.

Click on the link to learn how to optimize the storage on a device --> https://support.apple.com/HT201656

- If your device is low on storage, it automatically frees up space while installing an app, updating iOS or iPadOS, downloading music, recording videos, and more.

To make more storage available, your device can remove some of your items, like streamed music and videos, files in iCloud Drive, and parts of apps that aren't needed. It also removes temporary files and clears the cache on your device. But your device only removes items that can be downloaded again or that aren't needed anymore.

If your storage is full, use recommendations to optimize storage

Your device might offer recommendations for optimizing storage in the Storage section of Settings:

Tap Show All to see the recommendations for your device.

Read the description of each recommendation, then tap Enable to turn it on or tap the recommendation to review the contents that you can delete.

Optimization specifically with reference to "Set up and use iCloud Photos" - https://support.apple.com/HT204264

--> Save space on your device

iCloud Photos keeps all your photos and videos in their original, high-resolution version. You can save space on your device when you turn on Optimize Storage.

Manage your photo and video storage - "Learn how photos and videos use your iPhone, iPad, and iPod touch storage, ways to save space, and how to upgrade your iCloud storage if you’re running out."

https://support.apple.com/HT205703

Another way to free storage on a device is to transfer items to a computer and move them to locations which are not part of iCloud so they won't just sync back again. The items are archived on the computer and on backups you make of the computer. Read this article to learn how to sync your iPhone, iPad, or iPod using your computer - https://support.apple.com/HT201253

well thanks! your actually the first person to ever reply to me back, did not knew that this apple community thing was helpful after all, just tried it!