Drupal configured as IDP and need to send Logout Request as a post

I have configured Drupal as an identify provider using simplesamlphp along with drupalauth4ssp. Everything works fine for authenticating with service provide with 3rd party. The only issue I have is with logout. Currently, the initiated logout from Drupal IDP is sending a 'GET' and I need to send a 'POST'.

The 3rd party uses Keycloak. Based on the client the logout request is not being processed as a 'GET' and need to be a 'POST'. How do send a 'POST' or embedded POST details in the logout request?

I can see the logout process is being called in Drupal\drupalauth4ssp\SspHandler.php class.

NOTE:
We are working on upgrading [process is starting next week] to Drupal 10 and if there are no issues plan on upgrading to Drupal 11 immediately. However, SSO must be implemented now as part of current project.