No, you will not lose the photos in iCloud, that you removed from your iPhone while iCloud Photos has been turned off. But the photos currently in iCloud Photos will sync back to your iPhone from iCloud. You cannot have a different set of photos in iCloud and on your devices. iCloud Photos is not a separate external storage.
iCloud Photos is a syncing service, and its main purpose is to keep the Photos Libraries on all your synced devices identical. iCloud Photos is the central storage of your library and all synced devices will mirror this central storage. When you work with your photos on any of your devices, the changes will sync to iCloud and update the central Photos Library, and from there they will be synced and distributed to your other devices.
Your central iCloud Photos Library should be small enough to fit onto your device with the least storage. You may need to enable the "Optimize iPhone Storage" on your iPhone before you turn on iCloud Photos again. This way they photos will not sync back to the iPhone at the full, original resolution but as optimized, smaller versions just for browsing. The optimized versions will need less storage on your iPhone than in iCloud. You can reduce the size of the library on the iPhone up to 10% of the size in iCloud, as an estimate. If you can afford to have 50GB of photos on the iPhone you should keep no more than 500GB of photos in iCloud, but not more.