The user agent for Safari on IOS 11.3 [15E216] is Safari 11.0 but it says on https://webkit.org/blog/8142/intelligent-tracking-prevention-1-1/ "These updates to Intelligent Tracking Prevention are available in Safari 11.1 on iOS 11.3 beta" Full useragent Mozilla/5.0 (iPad; CPU OS 11_3 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/11.0 Mobile/15E148 Safari/604.1
I reported this on bug https://bugreport.apple.com as Bug ID 39014884
User Agent is frozen for privacy reasons, and will not be usable as a means of identifying features.