How to send an SMS to a Apple contact list?

Hey there, jcgmba98.

In order to send messages to multiple contacts, you can create a group using the steps below:

“Groups are listed in alphabetical order, with All Contacts at the top of the list.

1. In Contacts on iCloud.com, click in the sidebar, then choose New Group.
2. A new group is added, with a placeholder name.
3. Type a name for the group, then press Return or Enter.
4. To change the group name, double-click it and type a new name in the text field.” Create and manage groups of contacts on iCloud.com 

Since you cannot send a message to all contacts without first placing them in a group, and this is a feature you’d like, be sure to leave feedback for Apple: Product Feedback - Apple

We hope this helps to provide a more in depth answer. 

Sincerely.