Load webform submission How can I load a webform submission programmatically ?

I've tried : $webform_submission = WebformSubmission::load($sid);

but it return null.

I do this in a custom module call by an handler after webform submission.
I think you have to load sid like below

// Load submission using sid.
/** @var \Drupal\webform\WebformSubmissionInterface $webform_submission */
$webform_submission = \Drupal\webform\Entity\WebformSubmission::load($sid);