Giving updates to a really big game

I know it’s been boggling my mind since I’ve worked on this project.

Let’s say, for a game that has really large file size (the application/executable). How do you, unity developers, provide a minor-medium scale update? For example : new area/zone to an RPG game, some statistics fix to a certain item?

How do you do it if the game is deployed on iphone/ipad or any mobile devices?

As far as I know in Android, whenever an app got an update, you download the whole application. It’s fine if the app is around 5-10 megs, but if the app is as massive as 100 MB (is it even feasible for mobile platform?), how do you give an update in the most efficient way?

Thank you in advance for any inputs,

You’d use asset bundles.