On #iOS now has a feature called Siri shortcuts basically the phone assess your daily habits and suggests that you give certain actions a voice command. Suppose you send a WhatsApp message to someone often instead of opening the phone and opening WhatsApp to send a message you can just assign a short voice command to the action and Siri will do the rest. This feature can be accessed in Settings>Siri and Search and you do need Siri to be turned on for this to work obviously.
This coupled with Hey Siri function can help a lot if you use the right commands.