Custom template with CPT doesn’t display on frontend

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Using the following code I was able to load the custom template.

public function register_hook_callbacks(){
                    // Enqueue Styles & Scripts.
                    add_action( 'wp_enqueue_scripts', 
                    array( $this, 'enqueue_scripts' ) );

add_filter('template_include', 
    array( $this, 'view_project_template') 
);
    }