A short speech defending the role of the family has become Giorgia Meloni’s calling card at campaign rallies. “I am Giorgia. I am a woman. I am a mother. I am Italian. I am Christian. You can’t take this away from me,” she said. The woman widely expected to become Italy’s first female prime minister in Sunday’s election is far from typical, however: A far-right nationalist accused by political rivals and experts of spreading white supremacist ideas, who advocates naval blockades to stop unauthorized migration from Africa, Meloni is also a committed J.R.R. Tolkien fan and has embraced the internet...