I'm not sure if we have a firm age rating done yet but I do know that when we make content, we assume we are making content for an M rated game. I think the majority of the game could easily get away with a T rating but there are a few things that are a little extreme. For example, when you first make it to the ruined era very close to the start of the game, there are some people who have been killed "put on display" in a rather gruesome way. It's really easy to miss it and you actually have to zoom in to really tell what is going on but it is an example of something I wouldn't think most 11 year olds have seen before.
It's pretty low on the sexuality scale. Like, you can get your character down to basic, thematically appropriate underwear. There is some light incidental nudity that might pop up in the environment from time to time too.
So it's mostly just the violence which can be a little intense.
It's really hard to say if it would be appropriate or not and I could very easily be missing something. We took the M rating approach so we just wouldn't have to worry about it and can just make the game.
Hopefully that's some good info too help you make your decision.