Here's how to turn Siri off
completely on your iPhone
and turn off suggestions from Siri.
To turn off the Siri function completely
so it won't be activated by voice or using the side button,
open the settings app and tap on "Siri & Search."
Turn off the options "Listen for 'Hey Siri'"
and "Press Side Button for Siri" by swiping left.
Then tap on "Turn Off Siri."
If you just want to control
which suggestions Siri handles,
open the settings app and tap on "Siri & Search."
Under suggestions from Apple,
you can swipe left to turn off any of these suggestions.