How to fix Autocomplete template broken Porto Theme with Smile-SA elasticsuite
Create this file "default.xml" in your theme directory in this folder "{vendor}/{theme}Magento_Search/layout"
add this code in the file
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
<body>
<referenceContainer name="porto_header">
<block class="Smile\ElasticsuiteCore\Block\Search\Form\Autocomplete" name="top.search" as="topSearch" template="Smile_ElasticsuiteCore::search/form.mini.phtml">
<arguments>
<argument name="rendererList" xsi:type="array">
<item name="term" xsi:type="array">
<item name="title" xsi:type="string" translate="true">Search terms</item>
<item name="template" xsi:type="string">Smile_ElasticsuiteCore/autocomplete/term</item>
</item>
<item name="product" xsi:type="array">
<item name="title" xsi:type="string" translate="true">Products</item>
<item name="template" xsi:type="string">Smile_ElasticsuiteCatalog/autocomplete/product</item>
</item>
<item name="category" xsi:type="array">
<item name="title" xsi:type="string" translate="true">Categories</item>
<item name="template" xsi:type="string">Smile_ElasticsuiteCatalog/autocomplete/category</item>
</item>
<item name="product_attribute" xsi:type="array">
<item name="title" xsi:type="string" translate="true">Attributes</item>
<item name="template" xsi:type="string">Smile_ElasticsuiteCatalog/autocomplete/product-attribute</item>
<item name="titleRenderer" xsi:type="string">Smile_ElasticsuiteCatalog/js/autocomplete/product-attribute</item>
</item>
</argument>
</arguments>
</block>
</referenceContainer>
</body>
</page>
reference URL
https://github.com/Smile-SA/elasticsuite/issues/1112#issuecomment-426837492