How do I use voice assistant apps on my iPhone?

There are a few popular Voice Assistant options on iPhones including Apple’s Siri Voice Assistant. Follow the below links for support.

Apple “Siri”
Siri is Apple’s Voice Assistant built into the iPhone. Siri can make calls or send texts for you whether you are driving, have your hands full, or are simply on the go. It can even announce your messages on your AirPods. It also offers proactive suggestions — like texting someone that you are running late for a meeting — so you can stay in touch effortlessly.

Amazon “Alexa

Google “Google Assistant”