the layers are specific and unique to each architecture. you can google their papers if you want to know more.
your input (batchsize, 1, 224, 224) is fed through the layers in sequence - ie nn.Conv2d(1, 64, kernel_size=11, stride=4, padding=2), then nn.ReLU(inplace=True), and so on.
If you are modifying the original architecture, then you also have to make sure the resulting matrix operations are legal