If you would like to initialize a specific number of layers given a passed argument to the model, you could replace *layers with the initialization of new modules:
    def _make_branches(self, num_layers):
        branches = []
        for i in range(num_layers):
            branch = nn.Sequential(nn.Linear(1, 1)) # replace this with any new initialization
            branches.append(branch)
            branches = nn.ModuleList(branches)
        return branches