Is there any way to disable the live camera feed and pass the custom video feed as input in ARSession?
Disable live camera feed in ARSCNView?
I think what you are asking here is whether it is possible to provide an ARSession with an arbitrary video, and have it run plane detection, face tracking, and other ARSession features on that video. If that is what you are asking, no there is no api to do that, please file an enhancement request using Feedback Assistant.
There is a small wrinkle here, which is that you can provide "Replay Data" captured from the RealityComposer app on iPad as a run scheme option in Xcode for debugging / testing purposes. So if that fits your use case (i.e. you are trying to test your AR app), you should watch this video: https://developer.apple.com/videos/play/wwdc2021/10073/?time=423