The point of a giant IMAX screen with a super-sharp image is that it feels like you are actually there watching the events in real life instead of just seeing a picture on a movie screen. The giant super-sharp images are breathtaking.
Only four Hollywood movies were ever made this way: Dark Knight, Dark Knight Rises, Interstellar, and Dunkirk. I'm guessing there won't be another.
Dolby Atmos sound is something different. They have speakers all over the theater and a computer that understands the acoustics and speaker positions of that individual theater. In a similar way that a good stereo system can make a sound appear to be coming from a specific point in front of the listener, the computer can make a sound appear to be coming from any point around the theater or any point within the theater, and make the position of the sound move around.
A Dolby Atmos soundtrack doesn't simply say "here's the sounds for the left channel, the right channel, etc." Instead it gives each individual sound a position (that moves around as necessary), and the computer in each individual theater takes care of making the sound appear in the position that it is supposed to.
The result is, sounds move around the theater according to the action, and if something flies by you in the movie, you can really hear it fly by you.
In a way it does for sound what 3D does for the image.