The layers are initialized in some way after creation. E.g. the conv layer is initialized like this 5.3k.
However, it’s a good idea to use a suitable init function for your model.
Have a look at the init functions 7.2k.
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)