How do I create and name a group text on my iPhone 7?

Hi Monthos65,

Welcome to the Apple Community, where some of us do our best to help each other.

Wondering which operating system (Os number) you have on your iPhone, and what app you use, or is it SMS text.

Apple support have articles online to help: (click the blue links below):

Where possible, select your Os number at the top for the most precise info.

About iMessage and SMS/MMS

https://support.apple.com/en-au/HT207006

Group SMS. Send a group text message on your iPhone,

https://support.apple.com/en-us/HT202724

OR

Send a group Message in Message app on iPhone:

https://support.apple.com/en-au/guide/iphone/iph733450025/ios

Manage a group conversation in Messages on Mac:

You can send a message to a group of people,

then name your group conversation so that it’s easier to keep track of and find.

https://support.apple.com/en-au/guide/messages/ichtcd5737fa/mac

Name a group text message on your iPhone, iPad, or iPod touch

https://support.apple.com/en-us/HT211301

Change preferences in Messages on Mac:

https://support.apple.com/en-au/guide/messages/ichtcd5737fa/mac

Hope you can easily find what suits you best amongst these articles :)