The short answer is Yes. In fact, restoring from an iCloud or iTunes backup might lead to data loss because you need to reset your iPhone and the restored data will overwrite existing data.
For this reason, it is important to be prepared beforehand. You can keep a new backup so that you don’t lose the latest files on your device. Of course, this is a lot of trouble, which you will avoid if you learn how to restore backup from iCloud without resetting.