I haven't been able to find an answer to this question on Apple Support site. I found this article, but it only states the recommended distance to hold the phone to use FaceID, not the maximum reliable distance...
Face ID works best when the device is arm’s length or less from your face (25–50 cm away from your face).
- Does anyone know how far back the TrueDepth Camera/API can reliably detect a face/object? (Looking for a specific distance)