: The device will not boot on its own. Every time it restarts or dies, you must connect it to a computer and use a "Just Boot" command from your downgrade tool.
If you jailbreak your iPhone 5s on iOS 12, you can install themes from repositories (like Packix or BigBoss) that replicate the UI of iOS 7. You can find themes that restore the old Control Center design, the classic app icons, and the translucency effects. This gives you the aesthetic nostalgia without the functional nightmare of running a decade-old operating system.