Yes, Newfoundlands are great with kids. Newfoundlands form strong, protective bonds with their human family members and have loving and affectionate temperaments, making them excellent companions for children. Patient and low-key, these gentle giants are relatively tolerant of rough play (and other activities another breed might fight irksome).
That said, teaching children how to properly approach and handle dogs is crucial to ensure positive experiences for both the dog and the child. And, like all dogs, Newfoundlands need to be trained to behave gently with children. As with any breed, supervise interaction to keep both the child and dog safe.