https://www.howtogeek.com/826189/how-to-use-secret-conversations-on-facebook-messenger/
Yes, but it’s not new. It’s been around for approx 1 1/2 years.
I never said it was new. LOL
It isn’t done the same way. Now you have to start an encrypted chat and set a timer to make it disappear.
I’ve never had the need to do that. My days in the FBI are long over 
I tested yesterday and did not have to set any timer. 