Synergy with adaptations is a mug's game. Nobody has figured out how to do it.
The Adam West Batman show in the '1960s for instance brought a lot of interest in the Batman comics of the day but then the show ended and the readership of Batman fell really low and so the DC editors decided to greenlight a darker take and that led to the Denny O'Neill - Neal Adams - Englehart era that is basically the start of modern Batman. You know "Joker's Five Way Revenge". And that's what led to higher comics sales on Batman titles. The Christopher Reeve Superman movies, okay they were big for its time, but it didn't lead to super-normal or super-charged sales for the comics either at that time. Stuff like Byrne's THE MAN OF STEEL and later THE DEATH OF SUPERMAN did.
Ultimately what sells comics...are comics.
I mean the thing about bringing readers in from adaptations is that you are hoping or banking that the versions of characters they are introduced to will automatically be available to them on panels. No matter what you do, Robert Downey Jr. the actor cannot be translated to word balloons, panels and grids and splash images. If it's a video game...actually swinging around a digital Manhattan will always feel more boss than seeing an artist draw that on page. You are trying to introduce readers to another medium which doesn't have the properties and qualities of another.
The comics which really sold over to "Civilians" are stuff like Superman vs. The Amazing Spider-Man, Superman versus Muhammad Ali, Star Wars ('70s and also the Disney era), SECRET WARS 1984, Amazing Spider-Man Annual #21 (aka Peter and MJ get married which was the biggest comics event in the '80s in terms of prime time coverage), The Death of Superman, and also CIVIL WAR to some extent (mostly for Peter getting unmasked).
So basically it's unpredictable, spontaneous, and difficult to predict. Lighting in the bottle in the truest sense.