Exemple on how load template's files.

load-theme-files.php

<?php
$dependencies = [
	'inc' => [
		'assets',
		'manage-plugins',
		'options',
		'languages',
	],
	'theme' => [
		'wysiwyg',
		'title'
	]
];
foreach ( $dependencies as $folder => $files ) {
	if ( ! is_dir( dirname( __FILE__ ) . '/' . $folder ) ) {
		continue;
	}
	foreach ( $files as $file ) {
		get_template_part( $folder . '/' . $file );
	}
}