Set link field programatically

$node->set('field_link', [
  'uri' => 'http://google.com',
  'title' => 'Title',
  'options' => ['attributes' => [
  'target' => '_blank'
]]
]);

Links:
- https://www.drupal.org/forum/support/module-development-and-code-questions/2017-01-28/issue-updating-link-field