Which feature allows iPhone users to control other Apple devices with Siri?

The feature that allows iPhone users to control other Apple devices with Siri is HomeKit. HomeKit is Apple's smart home platform that integrates various home automation devices, such as smart lights, cameras, and thermostats, enabling them to be controlled using Siri voice commands. By setting up compatible devices within the Home app, users can create scenes and automate controls that can be triggered with voice commands, allowing for seamless interaction with multiple devices.

Other options serve different purposes. Screen Time is focused on managing device usage and setting restrictions, iCloud is a cloud storage service for syncing data across Apple devices, and Find My iPhone helps users locate lost devices but does not have functionality related to controlling other Apple devices.