How to turn off heads up notifications for messages on Galaxy S8?

I’m using an unlocked version of Galaxy S8 and its pre-installed messaging app called Messages. Every time there’s a new message, I will get a heads up notification at the top of the screen. That’s quite disturbing sometimes.

I tried to look for the option to turn that off. I turned off App icon badges, set the Importance (in the New messages settings) to make sound only and set ‘Do not show notifications’ in the On lock screen field, but none of them (as expected) helped.

Anyone has any ideas to stop the heads-up notifications for incoming messages