When you start a Live session on an iOS device with any major iOS version, you may be randomly allocated a device with any of the minor iOS versions applicable to that major version. The exact minor version for the session device may be confirmed via the device info dialog accessible via the Live in-session toolbar.
We do however currently provide limited support for launching a Live session with the exact minor iOS version required on a device. We currently offer two latest iPhone devices on the Live dashboard with two latest minor iOS versions (n & n-1) of the latest stable major iOS version.
For example, you may see iPhone 13 – iOS 15.5 & iPhone 13 – iOS 15.6 on the dashboard, 15.5 & 15.6 being the two latest minor iOS versions of the latest stable major iOS version (iOS 15) as of writing this.
Note, we keep cycling different iPhone devices between these latest minor iOS versions, hence you would only be able to start sessions with specific minor iOS version only on certain devices and only for the latest two minor iOS versions (n & n-1).