No, you won’t be able to set requires_grad=False for any non-leaf tensor and will get the following error:
RuntimeError: you can only change requires_grad flags of leaf variables. If you want to use a computed variable in a subgraph that doesn't require differentiation use var_no_grad = var.detach().

Use the torch.no_grad() block, which will make sure that Autograd won’t track any operations in this block, or detach() the tensor as described in the tutorial.