In 7.5 and 7.4 Server Administration Guide, it doesn't tell you how to use transient sessions:

https://access.redhat.com/documentation/en-us/red_hat_single_sign-on/7.5/html-single/server_administration_guide/index#transient-session

I believe the way to enable transient session for client credentials is to disable
"Use Refresh Tokens For Client Credentials Grant" in client config (this is the default value). I know the Docker authentication flow also uses transient sessions. I don't know if there are other ways to have transient sessions, so please check with engineering.