Dear User,
As I already mentioned above that this is not something related to theme. It depends on which translation plugin you are using and if that plugin has the capability to translate posts from backend
No idea about polylang
But in WPML plugin, is mainly used for multilinugal site. So everything will be like a copy of the original content, so you can basically create copies of your original content in different languages
Check this once: https://docs.wplms.io/translation-guide#wpml-wplms-compatibility
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