A CineControl App is already available from CineGizmo for controlling individual ARRI cameras. Now another version has been released, CineControl Multicam, which allows to control several cameras from the iPad. This app is also compatible with ARRI ALEXA Mini, ARRI ALEXA Mini LF and ARRI AMIRA.
Via WLAN -- the client/network infrastructure implemented in the cameras is used, with one camera acting as master -- you have access to many camera settings concerning exposure, recording formats, etc. They can either be set globally by copying parameters from one main camera to another, or individually for each connected camera. Likewise, recording can be started or stopped on all or individual cameras. Looks can also be installed, applied or customized. The recordings of the respective cameras can be played back remotely.
CineControl Multicam is currently still offered as a beta full version free of charge. It is not known how much the app will then cost regularly. An iPad with iOS version 11.0 or higher is required.