I am trying to find out if the accuracy, plane detection and World Tracking of the ARKit will be better in iPhone 8 Plus and iPhone X comparing to an iPhone 7.
I googled it and I read thru this webpage.
There is no indication of dual cameras, no explanation of specs of the camera and if the processor power or better cameras in lates devices will make ARKit more accurate (read here).
I am working on an accuracy-related arkit app and I'd like to know more about this topic.
ARKit doesn't use the dual camera, so there's no functional difference between an iPhone (pick a number) Plus or iPhone X and other devices.
Apple's marketing claims that iPhone 8 / 8 Plus and iPhone X are factory calibrated for better / more precise AR, but makes no definition of baseline vs improved precision to measure by.
That's about all Apple's said or is publicly known.
Beyond that, it's probably safe to assume that even if there's no difference to the world tracking algorithms and camera / motion sensor inputs to those algorithms, the increased CPU / GPU performance of A11 either gives your app more overhead to spend its performance budget on spiffy visual effects or lets you do more with AR before running the battery down. So you can say "better" about newer vs older devices, in general, but not necessarily in a way that has anything to do with algorithmic accuracy.
There's a tiny bit of room for ARKit to be "better" on, say, iPhone X or 8 Plus vs iPhone 8, and especially on iPad vs iPhone — and again it's more about performance differences than functional differences. Among devices of the same processor generation (A10, A11, etc), those devices with larger batteries and larger physical enclosures are less thermally constrained — so the combination of ARKit plus your rendering engine and game/app code will get to spend more time pushing the silicon at full speed than it will on a smaller device.