Children arguments when using :simple_one_for_one strategy

When using the :simple_one_for_one strategy, we specify the children to launch dynamically:

supervise([worker(FooServer, [])], strategy: :simple_one_for_one)

We then use something like the following to start children:

def start_child(arg1, arg2) do
  Supervisor.start_child(__MODULE__, [arg1, arg2])
end

The documentation states (emphasis mine):

In the case of :simple_one_for_one, the child specification defined in the supervisor will be used and instead of a child_spec, an arbitrary list of terms is expected. The child process will then be started by appending the given list to the existing function arguments in the child specification.

I tried the following

supervise([worker(FooServer, [:foo])], strategy: :simple_one_for_one)
#                             ^^^^
#                             "fixed" argument

But it seems arguments aren't appended, and I can't find how to access these fixed arguments. Is it even possible to do this?