Hello Chris Eason,
Thank you for posting in the Apple Support Communities. We'd like to offer our support with Messages.
First, we invite you to take a look at the Apple Support article below. It explains how to leave a group text message.
Leave a group text message on your iPhone, iPad, or iPod touch
Also, if you're starting a new message thread with a contact, you can start the message from the Contacts app by selecting the appropriate phone number. The section "Quickly reach a contact" in the Apple Support article below has a visual guide for starting a message in the Contacts app.
Add and use contact information on iPhone
We hope this information is useful. Kind regards.