Hello MrKwe,
Thanks for reaching out to the Apple Support Communities! From your message I understand you'd like for Siri to not read back the information that she retrieves under "Knowledge."
When you use the voice command "Hey Siri" the information will be read back to you. When you press the button to engage Siri, the information is not read back. I was able to verify this on my iPhone XS Max running iOS 13.3. You can check out more information in this article: Use Siri on all your Apple devices. You can also use the information in this article to Change Siri settings on iPhone.
Once Siri begins reading the information, "Hey Siri" will not stop the action. If this is a feature you'd like to suggest, be sure to head over to the Feedback site: Product Feedback - Apple. You can interrupt any action you've asked Siri to do by pressing the side button on your iPhone.
Cheers!