The layers are initialized in some way after creation. E.g. the conv layer is initialized like this.
However, it’s a good idea to use a suitable init function for your model.
Have a look at the init functions.
You can apply the weight inits like this:
def weights_init(m):
if isinstance(m, nn.Conv2d):
xavier(m.weight.data)
xavier(m.bias.data)
model.apply(weights_init)