Programatically add custom post type template files to WordPress

cpt-templates.php

<?php

/*
 * Plugin Name: Add cpt templates
 */

add_filter(
    'template_include',
    function ($template) {
        if (is_singular('cpt')) {
            return __DIR__ . '/cpt-template/single-cpt.php';
        }
        if (is_tax('cpt-category')) {
            return __DIR__ . '/cpt-template/category-cpt.php';
        }
        if (is_post_type_archive('cpt')) {
            return __DIR__ . '/cpt-template/archive-cpt.php';
        }
        return $template;
    },
    10,
    1
);