You can directly retrive the weights or bias vectors by weight or bias attribute like this:
import torch.nn as nn


class MyModel(nn.Module):
    def __init__(self):
        super().__init__()
        self.cnn = nn.Sequential(
            nn.Conv2d(3, 3, 1),
            nn.ReLU()
        )
        self.fc = nn.Linear(10, 10)


model = MyModel()
conv_weight = model.cnn[0].weight
fc_bias = model.fc.bias