The iPhone 5s is a 64-bit device. Some older downgrade tools (like Odysseus) were designed for 32-bit devices (iPhone 5). You must use tools compatible with 64-bit checkm8 exploits (like futurerestore ).
Your iPhone 5s and a MFi-certified USB-A to Lightning cable. How to Downgrade iPhone 5S from iOS 12.5.7 to iOS 10.3.3! iphone 5s downgrade to 10.3.3 windows
Before you start, know this: Apple no longer officially signs iOS 10.3.3 for the iPhone 5s. That means you cannot simply press “Restore” in iTunes. However, the iPhone 5s is unique because it has a dual-boot exploit (the OTA update mechanism). Using a tool called LeetDown , you can downgrade to the specific build of 10.3.3 that Apple still secretly signs for OTA updates. The iPhone 5s is a 64-bit device