I got my ipa size for Garden Wars to around 85-91MB on iOS (depending on device) & 47MB on Android. Was gonna write about it here but thought it would make a useful blog post 
Reducing the size of your iOS or Android game (Unreal Engine 4)
Of course, it’s a relatively small and simple game - all unlit shaders etc (but still a lot more complex than tappy chicken).
Hope the info there helps!