Check the following root script to create customer programmatically:

use MagentoFrameworkAppBootstrap;
 
require 'app/bootstrap.php';
$bootstrap = Bootstrap::create(BP, $_SERVER);
$objectManager = $bootstrap->getObjectManager();
$state = $objectManager->get('MagentoFrameworkAppState');
$state->setAreaCode('frontend');
 
 
$storeManager = $objectManager->get('MagentoStoreModelStoreManagerInterface');
$storeId = $storeManager->getStore()->getId();
 
$websiteId = $storeManager->getStore($storeId)->getWebsiteId();
 
try {
    $customer = $objectManager->get('MagentoCustomerApiDataCustomerInterfaceFactory')->create();
    $customer->setWebsiteId($websiteId);
    $email = 'ex00@example.com';
    $customer->setEmail($email);
    $customer->setFirstname("example first");
    $customer->setLastname("example last");
    $hashedPassword = $objectManager->get('MagentoFrameworkEncryptionEncryptorInterface')->getHash('MyNewPass', true);
 
    $objectManager->get('MagentoCustomerApiCustomerRepositoryInterface')->save($customer, $hashedPassword);
 
    $customer = $objectManager->get('MagentoCustomerModelCustomerFactory')->create();
    $customer->setWebsiteId($websiteId)->loadByEmail($email);
} catch (Exception $e) {
    echo $e->getMessage();
}

Run the above script code in a loop and create multiple customers at a time, by changing the email ID every time.

That’s it!