Since iOS 11, BT/WiFi OFF buttons were neutered to what I call "F^@& Off". Requiring either a cumbersome journey into Settings, or using the Shortcut App to make BT/WiFi OFF buttons for your homescreen

This Quora user more helpfully explains: "Almost entirely to preserve a bunch of other features that depend on Bluetooth/Wi-Fi, including AirPlay, AirDrop, Apple Watch, Apple Pencil, and Handoff." https://www.quora.com/Why-does-Apple-not-actually-disable-Wi...

Thankfully, the Cell Data button is still On/OFF