Create catalog_category_view.xml in your theme
app/design/frontendcode/Vendor/themeModule/Magento_Catalogview/frontend/layout/catalog_category_view.xml
<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="2columns-left" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceContainer name="content">
<block class="Magento\Framework\View\Element\Template" name="custom.block" template="Magento_Catalogtemplate="Vendor_Module::myCustomFile.phtml" />
</referenceContainer>
</body>
</page>
Now create myCustomFile.phtml and place your custom code
app/design/frontendcode/Vendor/themeModule/Magento_Catalogview/frontend/templates/myCustomFile.phtml
<?php
echo "This is my custom file for product list page";
?>