If you don’t use Siri often, you probably don’t need your iPhone to be continually listening for the “Hey Siri” command. After all, on every new iPhone, you can just long-press the side button to activate the assistant, freeing up battery life dedicated to voice command detection.

Instructions:
On your iPhone, navigate to Settings > Siri & Search and select “Listen for”.

Select “Off” from there to prevent using any of the hot words to activate Siri.