Preset paragraph on node creation

my_module.module

<?php

use Drupal\node\Entity\Node;

/**
 * Implements hook_ENTITY_TYPE_create().
 */
function my_module_node_create(Node $node) {
  if ($node->bundle() == 'my_bundle') {
    $field = $node->get('field_my_paragraph_field');
    if ($field->isEmpty()) {
      $paragraphs = \Drupal::entityTypeManager()->getStorage('paragraph')->create([
        'type' => 'my_paragraph_type',
      ]);
      $field->appendItem($paragraphs);
    }
  }
}