Hello India 42,
If sounds like you've already had the chance to follow the steps below: How to change Siri volume - Apple Support
You can ask Siri to change your volume settings. Just say "Hey Siri, speak louder" or "Hey Siri, speak quieter."
If you want to change the volume when Siri is speaking or when you're using headphones, press the Volume buttons on the side of your iPhone.
Let's also use the steps below to make sure that your iPhone is all up to date: Update your iPhone or iPad - Apple Support
1. Back up your device using iCloud or your computer.
2. Plug your device into power and connect to the internet with Wi-Fi.
3. Go to Settings > General, then tap Software Update.
4. If you see more than one software update option available, choose the one that you want to install.
5. Tap Install Now. If you see Download and Install instead, tap it to download the update, enter your passcode, then tap Install Now. If you don't know your passcode, learn what to do.
If your iPhone is all up to date, let's restart: Restart your iPhone - Apple Support
Updating and restarting can sometimes help address odd behaviors.
Should that behavior with Siri still persist, you'll want to reach out to Apple Support: Apple Support They'll be in the best position to look into this further.
Take care.
