Revision 16bf306d-53d0-42ec-9584-a66ffa5fd3c3

Use below code for your layout customer_account_login.xml file

        <?xml version="1.0"?>
    <page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" layout="1column" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
        <body>
            <referenceBlock name="customer_form_login">
                <action method="setTemplate">
                    <argument name="template" xsi:type="string">Magento_Customer::form/login123.phtml</argument>
                </action>
            </referenceBlock>
        </body>
    </page>