I assume you’re talking about the “Shop” page which is created by woocommerce. I’ve tested the cart, checkout and my account page and they seem to work fine with custom templates.
For the shop page, copy the file page-full.php from the theme then place it on a child-theme. Then rename that file to page-shop.php. The shop page should now be full-width.
Open page-shop.php and remove this line (Line 1)
<?php // Template Name: Full, No Sidebar ?>
This is so that normal pages don’t use this template and is only reserved for the woocommerce shop page.