Message template concept only apply to WhatsApp API channel.
Message templates are used to initiate conversations with customers. Unlike other types of messages, message templates are the only type of message that can be sent to customers who have yet to initiate a conversation with you, or who have not sent you a message in an existing conversation thread within the last 24 hours.
Message templates must be approved before you can send them to customers. In addition, templates may be disabled automatically based on customer feedback. Once disabled, a message template cannot be sent to customers again until its quality rating has improved or it no longer violates our business or commerce policies.
The guidelines from WhatsApp official.
https://developers.facebook.com/docs/whatsapp/message-templates/guidelines
Settings > Message Templates > Create
Key points:
Message Templates support variables which means that the variables can be filled by any text when sending out. The syntax will be {{1}} with the numbers. For instances, if your body messages contains two variables , it will be {{1}} , {{2}} * Variable parameters must in sequential. For example, {{1}}, {{2}}, {{3}}, {{4}}
Message Template contains Header, Body, Footer, and Action Buttons
Message Template will submit to WhatsApp review and approval, only the approved template can be used.
Check the status by click Sync Button. Normally the approval time can from several minutes to days.
Suggestions:
Create a generic message template. e.g.
Hi
{{1}}
feel free to let me know if any questions.
Official Guideline for creating template message
https://www.facebook.com/business/help/2055875911147364?id=2129163877102343