oliverdavies.uk-drupal-old/web/modules/custom/blog/opdavies_blog.module

<?php

/**
 * @file
 * Custom blog code.
 */

use Drupal\Core\Url;
use Drupal\node\NodeInterface;

/**
 * Implements hook_node_links_alter().
 */
function opdavies_blog_node_links_alter(array &$links, NodeInterface $node): void {
  if (!method_exists($node, 'getExternalLink')) {
    return;
  }

  if ($link = $node->getExternalLink()) {
    $links['node']['#links']['node-readmore']['url'] = Url::fromUri($link['uri']);
    $links['node']['#links']['node-readmore']['title'] = t('Read more<span class="visually-hidden"> about @title</span> (<span class="visually-hidden">on </span>@domain)', [
      '@domain' => $link['title'],
      '@title' => $node->label(),
    ]);
  }
}

/**
 * Implements hook_preprocess_HOOK().
 */
function opdavies_blog_preprocess_block(array &$variables): void {
  // Add the 'markup' class to blocks.
  if (in_array($variables['plugin_id'], ['views_block:featured_blog_posts-block_1'])) {
    $variables['attributes']['class'][] = 'markup';
  }
}

/**
 * Implements hook_preprocess_HOOK().
 */
function opdavies_blog_preprocess_node(array &$variables): void {
  if (!method_exists($variables['node'], 'getExternalLink')) {
    return;
  }

  if ($link = $variables['node']->getExternalLink()) {
    $variables['url'] = $link['uri'];
  }
}