Code snippet that can be used to update users programmatically in Drupal 8.
Add the following code inside a function where you want to update users.
$uid = \Drupal::currentUser()->id();
$user = \Drupal\user\Entity\User::load($uid);
$user->setPassword("example");
$user->setEmail("example@gmail.com");
$user->setUsername("example");
// Set the field value new value.
// $user->set('field_example', "field_example");
$user->save();
