Use node_edit_form theme for node forms

node.module defines a theme hook for node_edit_form, but it is not used by default.

Claro applies it to node forms with:

function claro_form_node_form_alter(&$form, FormStateInterface $form_state) {
  $form['#theme'] = ['node_edit_form'];
  $form['#attached']['library'][] = 'claro/node-form';

  $form['advanced']['#type'] = 'container';
  $form['advanced']['#accordion'] = TRUE;
  $form['meta']['#type'] = 'container';
  $form['meta']['#access'] = TRUE;

  $form['revision_information']['#type'] = 'container';
  $form['revision_information']['#group'] = 'meta';
  $form['revision_information']['#attributes']['class'][] = 'entity-meta__revision';
}

Starterkit Theme has a template that moves the vertical tabs into a sidebar.