The Peloton Bike+ has a "Auto-Follow" feature that will allow that Peloton to control your resistance automatically. This feature is only available on on-demand rides that have target metrics added. Auto-Follow is not available on live rides. Also, not all on-demand rides get target metrics added - power zone rides, for example, do not, so auto-follow will not work on power zone rides.
Use of the auto-follow feature is optional, but when it is turned on, it will change your resistance as the instructor calls out changes. You can click one button on the screen at any point to turn it on and off, and even with it on, you can override it manually with the resistance knob.
The original Peloton bike does not have the ability to automatically control your resistance.
The Peloton Tread and Peloton Tread+ also do not have the ability to control your resistance automatically.