load-cpt-template.php

<?php
add_filter( 'template_include', 'your_custom_cpt_template', 99 );
/**
 * Load an alternative template file for a given post type
 * 
 * @param  string $template		path to the default template
 * @return string $template		path to the default template
 * @return string $custom_template	path to the custom template
 */
function your_custom_cpt_template( $template ) {
	if ( ! is_singular( array( 'your_cpt_1', 'your_cpt_2' ) ) ) { // Change 'your_cpt_x' to the slug of your custom post type(s)
		return $template;
	}

	$custom_template = locate_template( array( 'your_cpt_template.php') ); // Change 'your_cpt_template.php' to the file name of your template (e.g., 'page_landing.php')
    
	if ( ! $custom_template ) {
		return $template;
	}

	return $custom_template;
}