You easily can assign a different theme in selected WordPress posts and pages.
Page Theme is a free WordPress plugin by Chris Ravenscroft. This plugin allows you to select a different theme for your individual blog posts and pages.
Installation & Usage:
Step-1 Install and activate it, then visit Dashboard-> Appearance -> Page Theme and enable Page Theme on Posts and Pages
Step-5 Click Set Theme button.
For selecting a theme for any particular page, visit Dashboard -> Pages -> All Pages list and set the theme from theme column.