iCloud Photos

Per - Change your iCloud feature settings - Apple Support.....

"When you turn off an iCloud feature on a device, information stored only in iCloud for that feature is no longer available on the device. If you turn off Mail, Contacts, Calendars, Notes, Reminders, or iCloud Photos on just one device, you can still view and change your information on iCloud.com and on another device you set up for that feature.

Sometimes when you turn off an iCloud feature on a device, you can choose to keep a copy of the feature’s information on that device. The copied information isn’t kept in sync with iCloud. If you turn off Mail, Contacts, Calendars, and Tasks in iCloud for Windows on a Windows computer, information stored in iCloud remains available in Microsoft Outlook, but it isn’t kept up to date with your other devices. 

Before you turn off a particular feature on all of your devices, or before turning off iCloud completely, you can make a copy of the information you keep in iCloud on your computer. If you want to delete information and backups stored in iCloud, learn how to manage your iCloud storage."