What do haptics actually do on an iPhone?

the Haptic Touch speed is the other one to know. Settings > Accessibility > Touch > Haptic Touch lets you set how long you hold before the menu pops up. switching it to fast made the phone feel a lot snappier for me. there's also a Vibration switch on that same Touch screen that kills every vibration, but it turns off emergency alert vibrations as well, so i wouldn't use that one.

They're the small taps you feel instead of hear. The obvious ones are the click when you long-press an icon, the tick when you flick through a timer or date wheel, and the buzz when Apple Pay goes through. You can switch most of them off in Settings > Sounds & Haptics > System Haptics. Keyboard feedback is separate, in the same menu under Keyboard Feedback, and it's off unless you turned it on. Ringer and alert vibration is its own setting again, so turning off system haptics won't stop the phone buzzing for calls.