Magento 2.3 – Search Results Relevance with Elasticsearch

Give a try below to check atleast if ElasticSearch returns some results or not?

File: Check\Es\etc\di.xml

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">

    <type name="Magento\Elasticsearch\SearchAdapter\ResponseFactory">
      <plugin name="ESChecker::willReturnsDocuments" type="Check\Es\Plugin\ESResponseCheck" sortOrder="1" disabled="false" />
    </type>
</config>

File: Check\Es\Plugin\ESResponseCheck.php

<?php
namespace Check\Es\Plugin;

use Magento\Elasticsearch\SearchAdapter;
use Psr\Log\LoggerInterface;


class ESResponseCheck
{

    protected $logger;

    public function __construct(
        LoggerInterface $logger        
    ) {
        $this->logger = $logger;

    }

    public function beforeCreate(\Magento\Elasticsearch\SearchAdapter\ResponseFactory $subject, $result)
    {
       if(!is_array($result) || empty($result)) return false;
       foreach ($result['documents'] as $rawDocument) {
            $this->logger->debug('ELASTIC_SEARCH_DEBUG_CODE',$rawDocument);   
       }            

    }
}

Clear the cache and catalog search reindexing

Perform any search terms and check var/debug.log file found in the Magento root directory.

In the debug.log file look for the product IDs returns from the ElasticSearch.

Also, check below URL for further info - https://magento.stackexchange.com/a/285358/34579

Check in your env.php file if you have

  'catalog' => [
            'search' => [
                'enable_eav_indexer' => '1',
                'engine' => 'elasticsearch7',
                'elasticsearch7_server_hostname' => 'elasticsearch'
            ]
        ],