With games that are not Battle Royale focus, we tend to see the special mode get added later on after the game has been released for a while to make sure there is no issue but for Call of Duty: Modern Warfare, it looks like they will be offering it at launch.
Activision is talking battle royale to the next level as they announce that the game will come with a 100 player mode will be available at launch. Some fans notice that the developer mentioned “select multiplayer experiences” here which means there might be more than one mode that supports up to 100 players at a time.
Of course, at this point, it is just speculation that it will be a battle royale mode as Activision did not say that it is. Just because it can support up to 100 players does not mean it will be a battle royale so we will have to wait and see.
Call of Duty: Modern Warfare will be released on the 25th of October.