Implement Template Files in Theme Code?

I need to add informations per php, for example to add the price from a meta box field (because kindle books don’t have price infos).

So is there a way to make the code from the template files work directly in theme files like the single.php / archive.php etc.?

Alternatively, is there a way to add php code to the template files?

https://ww.wp.xz.cn/plugins/amazonsimpleadmin/