Astra Pro plugin provides Custom Layouts and Page Header addon. You can create custom designs with these addons. Sometimes you may need to duplicate them, tweak a little and use again on the same or different sites. Below are some suggestions.
Duplicate Custom Layouts and Page Headers
You can use the external plugin for this. A plugin like Duplicate Page and Post allows duplicating Astra’s Custom Layouts and Page Headers. Just install the plugin, it will offer the option for each post.