There are web-based emulators (like the one popularized by developer Riley Testut or archive sites) that allow you to play old iOS games or experience the interface directly in your Chrome or Safari browser. This is much safer than installing an APK.
High-resolution recreations of the original flat icons for apps like Mail, Safari, and Messages. iOS 7 Typography: iphone 5 ios 7 emulator v2 apk
The harsh reality is that Apple’s operating system is proprietary and designed exclusively for its own hardware. What you will find are launchers, themes, and skinning apps that simulate the look of iOS 7, but they do not emulate the operating system itself. There are web-based emulators (like the one popularized