I can't say that I've done something like this at work as my working experience is rather than logistics, but saying that when we did have big issues maybe even to big, what we would do is try to break them down into smaller ones so it reduces the natural anxiety.
I've always been thrown in the deep end, and even now i'm trying to build a platform which is the biggest thing I've built there are days it's overwhelming but I know its something that I must do, if it takes me longer to do it then that's fine :)
I wouldn't think impostor syndrome comes into play, this only comes into play when you might have someone who says that they can code in xyz but they cant. But remember its always important, if you do feel that its a bit too overwhelming, just ask if maybe the project or item can be split and you might be able to manage it a bit easier :)