I don't really think there is a way right now, unless you can somehow find it in the store.
There's a website ( http://extreme-modding.de/PS4/database/themes.html ) that has a link to the package file for the theme, but I don't think you can actually do anything with it, pretty sure Sony requires all themes to be installed through the store.
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There's a website ( http://extreme-modding.de/PS4/database/themes.html ) that has a link to the package file for the theme, but I don't think you can actually do anything with it, pretty sure Sony requires all themes to be installed through the store.