SPOILER ALERT: Contains details from Episode 6 of “House of the Dragon,” airing Sunday, Sept. 25, on HBO and HBO Max.Episode 6 of “House of the Dragon” introduces a dramatic 10-year time jump. After a decade, expect a lot of changes: For starters, Princess Rhaenyra and Queen Alicent are portrayed by new actresses; the former is now played by Emma D’Arcy instead of Milly Alcock; the latter by Olivia Cooke instead of Emily Carey. Alicent’s kids, who we last saw as babies and toddlers, are now bratty teenagers.