Hello, @svenmoller,
Actually, there is no need to customize the theme core files, by default our PORTO theme provides an option in which you can design a single product page using the page builder plugin you are using on the site as per your need.
Simply navigate to the Dashboard >> Porto >>Template Builder >> Single Product >> Add new >> https://postimg.cc/r0ZZHD7B >> create a new layout when the editor opens you have the control to design according to the needs.
You can set the product meta after the add-to-cart as well. Here is an example: https://postimg.cc/HcL8xnjs I hope you understand.
Further, I have attached a detailed article on it for your better understanding: https://www.portotheme.com/wordpress/porto/documentation/single-product-builder-elements/
Best Regards,
PThemes Team.
