Comment ajouter le phtml à l'aide de XML Magento 2

<referenceContainer name="after.body.start">
    <block class="Magento\Framework\View\Element\Template" 
           name="custom.file" 
           before="-" 
           template="Magento_Theme::html/custom.phtml"
    />
</referenceContainer>
Combative Crocodile