Nested Task<T> calls without async/await

This is kind of related to the following post: Why use Async/await all the way down

I am curious what happens in the following scenario:

Updated due to comment:

async Task FooAsync()
{
    await Func1();
    // do other stuff
}

Task Func1()
{
    return Func2();
}

async Task Func2()
{
    await tcpClient.SendAsync();
    // do other stuff
}

Does this whole process becomes a blocking call? Or because Func1() is actually awaited on, the UI can go and work on something else? Ultimately is it necessary to add the async/await on Func1()? I've played around with it but I don't actually notice any difference, hence the question. Any insight would be great, thanks!