There is no strict order. It might be the same order as the registration. But someone can register the last layer first and then this will be wrong 
Note that for some models, the output size will also depend on the input that is given (fully convolutional neural nets for example).
But if you know the input size, you can create a dummy input Tensor that you forward to see the output size. That will work for most network (except for the weird ones where the output depends on the values in the input Tensor).