To run Augmented Reality Apps, you'll need two things; firstly you'll need to have an iPhone or iPad with an A9, A10 or A11 chip. Secondly, you'll need to be running the latest version of iOS 11.
The devices that use A9, A10 and A11 chips are:
- iPhone 6s and 6s Plus
- iPhone 7 and 7 Plus
- iPhone SE
- iPad Pro (9.7, 10.5 or 12.9) – both first-gen and 2nd-gen
- iPad (2017)
- iPhone 8 and 8 Plus
- iPhone X
So, if you've got an iPhone, that's at least a 6S, and you're running iOS 11. You'll be fine!