How to stop syncing photos on 2 devices

What is the situation on your iPad? Do you have enough storage on the iPad to download all photos to the iPad and then turn off iCloud Photos only on the iPad? https://help.apple.com/ipad/12/#/iPad3d83fbbbhttps://help.apple.com/ipad/12/#/iPad3d83fbbb

On the iPad:

Go to Settings > [your name] > iCloud > Photos, then tap "download and keep originals".

Now wait for all photos to download to the iPad.

Go to Settings > [your name] > iCloud > Photos, then turn off iCloud Photos.

iCloud Photos will still be enabled on your iPhone.

but I want to know how I can still sync with iCloud on my phone (in order for the pics not to get lost and save space)

iCloud Photos will keep your photos save , so you can restore them from iCloud, if your iPhone gets lost, stolen, or damaged. But it will not protect you from user errors. If you accidentally delete your photos, they will be gone. The iCloud backup of your iPhone will not include the photos, if you are using iCloud. You will have no backup at all, unless you regularly save your photos on a computer.