magento2-modules/app/code/Mageplaza/Seo/Observer/CmsPageLoadAfter.php

<?php

namespace Mageplaza\Seo\Observer;

use Magento\Framework\Event\ObserverInterface;
use Magento\Framework\Event\Observer;
use Mageplaza\Seo\Helper\Data as SeoHelper;
use Magento\Framework\View\Page\Config;
use Magento\Framework\Registry;
use Magento\Framework\ObjectManagerInterface;
use Magento\Framework\UrlInterface;
use Magento\Framework\View\Context;
use Magento\Framework\App\Request\Http as Url;
use Magento\Store\Model\Group;

class CmsPageLoadAfter implements ObserverInterface
{
    protected $helper;
    protected $pageConfig;
    protected $registry;
    protected $objectManager;
    protected $urlManager;
    protected $context;
    protected $url;
    protected $storeGroup;

    public function __construct(
        SeoHelper $helper,
        Config $pageConfig,
        Registry $registry,
        ObjectManagerInterface $objectManager,
        UrlInterface $urlManager,
        Context $context,
        Url $url,
        Group $storeGroup
    ) {
    
        $this->helper        = $helper;
        $this->pageConfig    = $pageConfig;
        $this->registry      = $registry;
        $this->objectManager = $objectManager;
        $this->urlManager    = $urlManager;
        $this->context       = $context;
        $this->url           = $url;
        $this->storeGroup    = $storeGroup;
    }

    /**
     * @param \Magento\Framework\Event\Observer $observer
     *
     * @return $this
     */
    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        $action = $observer->getEvent()->getFullActionName();

        if ($action == 'cms_index_index') {
            $page = $observer->getData('page');

            $metaTitle       = $this->helper->getGeneralConfig('meta_title');
            $metaDescription = $this->helper->getGeneralConfig('meta_description');

            if ($metaTitle) {
                $page->setMetaTitle($metaTitle);
            }
            if ($metaDescription) {
                $page->setMetaDescription($metaDescription);
            }
        }

        return $this;
    }

    /**
     * @return mixed
     */
    public function getBaseUrl()
    {
        return $this->objectManager->get(
            'Magento\Store\Model\StoreManagerInterface'
        )->getStore()->getBaseUrl();
    }
}