drupal/core/modules/taxonomy/taxonomy.local_actions.yml

taxonomy_add_vocabulary_local_action:
  route_name: taxonomy.vocabulary_add
  title: 'Add vocabulary'
  appears_on:
    - taxonomy.vocabulary_list

taxonomy.term_add:
  route_name: taxonomy.term_add
  title: 'Add term'
  appears_on:
    - taxonomy.overview_terms