What if can we talk to siri without touching phone ?

Yes - you can talk to Siri without touching the phone. It is a feature called "Hey Siri":

You can use Siri without pressing the Home or Side button. First, make sure that "Hey Siri" is on under Settings > Siri & Search > Listen for "Hey Siri." Then say "Hey Siri" and ask your question. For example, you can say "Hey Siri, how's the weather?"

If you have an iPhone 6s or later, iPad (6th generation), or iPad Pro*, you can use "Hey Siri" whenever you want. If you have an iPhone 6 or earlier, or another iPad or iPod touch model, you need to plug your device into power first.

Best,

GB

It's already possible. With "Hey Siri" turned on, you can activate Siri simply by saying Hey Siri. No need to touch the iPhone.

See here for details: Use Siri on your iPhone, iPad, or iPod touch - Apple Support