Custom Post Type Templates maybe_get_cpt_template

maybe_get_cpt_template.php

<?php
public function maybe_get_cpt_template( $original_template ) {
	$object = get_queried_object();
	// Check if post type template
	if ( is_object( $object ) && is_a( $object, 'WP_Post' ) && in_array( $object->post_type, $this->post_types ) ) {
		$maybe_template = get_post_meta( $object->ID, '_wp_page_template', true );
		if ( $maybe_template ) {
			$template = get_query_template( $object->post_type, $maybe_template );
			if ( file_exists( $template ) ) {
				return $template;
			}
		}
	}
	return $original_template;
}

public function register_meta_boxes() {
    add_meta_box( 'post_type_templates', 'Choose a Template Then Update', array( $this, 'post_type_choose_templates' ), $this->post_types, 'side', 'low' );
}