iOS sandboxes all application data. Without a jailbreak or specialized desktop backup software (like iMazing), you cannot directly browse the file system to extract the raw save file.
Relying solely on your phone's local storage is risky. If you uninstall the app or clear your device cache without a cloud link, your save file will be permanently deleted. The Best Ways to Secure Your Save File angry birds 2 save file best
Whatever path you choose, remember these golden rules: iOS sandboxes all application data