This plugin adds Page Templates feature to Posts and Custom Post Types. No settings needed.
Templatify gives the ability to select custom templates for each post type, even custom post types, as for Pages.
Once you activate Templatify, a “Select Template” box will appear in every post edit screen filled with Pages Templates.
You can also add post type specific templates: just add “Template Post Type” header (similar to “Template Name” header for custom templates) on your custom template to see it in the dropdown selector (see Screenshots).