Create node programmatically

$node = Node::create([
  'type' => 'product',
  'title'  => $offer_name,
  'add_to_cart_price' => $offer_price,
  'field_offer_id' => $offer_id,
  'body' => $offer_desc . $params,
  'field_category' => [['target_id' => $category_term->id()]],
]);
$node->body->format = 'full_html';
$node->save();