You can find "The Purge" and the rest of Season 9 on several streaming platforms and digital stores:
You can buy the episode directly through the Apple TV Store. Watch www xrysoi se Supernatural S09E13
If you're looking for more info on the Winchester lore, fans often visit the Supernatural Wiki for detailed breakdowns of every monster and myth. Mark Watches 'Supernatural': S09E13 – The Purge | You can find "The Purge" and the rest
Available for purchase per episode or as a complete season on Amazon Prime Video. Watch www xrysoi se Supernatural S09E13