Obviously Venom would need to be introduced beforehand since in the comics, that symbiote “gave birth” to the one that bonded with serial killer Cletus Kasady and turned him into Carnage.
While the chances of a Maximum Carnage movie being made (or any solo Carnage movie for that matter) are unlikely, it’s not impossible that Carnage could be introduced in a future Spider-Man movie.
Once that was dealt with, then the door would be open to pit Carnage against Tom Holland’s Peter Parker in a Spider-Man: Homecoming sequel.
Carnage has been seen in numerous animated series and video games since being introduced in the early 1990s, so he’s earned enough cred to be brought into live action.