Dual Booting 64 Bit devices
Previously, all public information regarding iOS dual booting has been for 32bit devices, e. g. iPhone 5 and older, and iPad 4th Generation and older. In this guide, we are going to be dual booting 64 bit devices, (iPhone 5s and newer). Keep in mind, the information you will see here focuses on APFS, Apple's new partition scheme, instead of old style HFS+. Just a little note, it should be possible to dual boot any version, provided the currently installed SEP is compatible with the target operating system. At the time of this article, we can only boot with the checkm8 exploit, which limits us to tethered boots of the secondary operating system.
There's no warranty given. Follow this guide on your own risk. If something goes wrong, a restore should fix everything.