Siri's voice commands let you cut down on physical interactions with the phone, which is a great way to simplify an iPhone for the elderly. Enabling Voice Dial grants Siri the ability to make calls from lock screen.

Here's how to enable it:

1. Go to Settings.
2. Select Face ID & Passcode or Touch ID & Passcode, depending on your device.
3. Confirm your current passcode to continue.
4. Select Voice Dial from the list to toggle it on.
5. You can now tell Siri to call a contact or phone number from the lock screen.