The WC single item template is located at:

```yoursite.com/wp-content/plugins/woocommerce/templates/single-product.php```

See this documentation:

https://docs.woocommerce.com/document/template-structure/

So, you would want to move any of those templates to your child theme under ```/wp-content/themes/your-child-theme/woocommerce/[any_template_you_want]```

So, for example, if you wanted to edit the single-product.php but safe from WC updates, you would put the file in this directory and do your mods:

```www.yoursite.com/wp-content/themes/your_child_theme/woocommerce/single-product.php```

Last thing to mention here is keep the directory structure as well.  So, if you want to edit something in the 'email' folder, it would be like this:

```www.yoursite.com/wp-content/themes/your_child_theme/woocommerce/emails/admin-new-order.php``` (just for example sake)

So, copy any templates you want to modify using that documentation above and you will be safe from any updates over time.