Native blog controls can be found under Pro > Theme Options > Blog and Pro > Theme Options > Portfolio for Portfolio.
The portfolio template file is under
\pro\framework\views\global find the _portfolio.php file for portfolio template, and the _index.php file for the blog template. Careful about editing a template though it might break your site, please follow the Customizations Best Practices.
Please be reminded that we do not provide support for customization.
I would still advise the Essential Grid extensions if you want to able to edit your index pages in Content Builder.
Have a good night too.