Please mention the reference container where do you want to add the store switcher. See the below code for reference:
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceContainer name="footer">
<block class="Magento\Store\Block\Switcher" name="store_switcher" as="store_switcher" after="footer_links" template="Magento_Store::switch/stores.phtml"/>
</referenceContainer>
</body>
</page>
You need to mention 2 things one is reference container where you want to show the block and second one is the after="footer_links"(Not necessary but needed if you want to order the switcher position through xml).
Hope this helps.