degov-8.x-2.0/modules/degov_social_media_youtube/degov_social_media_youtube.install

<?php

function degov_social_media_youtube_install() {
  $config = \Drupal::service('config.factory')->getEditable('degov_social_media_youtube.settings');
  $config->set('api_key', '')->save();
  $config->set('channel', '')->save();
  $config->set('number_of_videos', '5')->save();
}