Send Whatsapp with API including custom placeholders

Send Whatsapp with API including custom placeholders

Is is possible to initiate a session on whatsapp IM channel with a template that includes params (placeholders) that are passed on the API call?
This is very usefull to send a Utility message for a transactional notification including an order number or any other variables.
I found a meta param in initiateSession /api/v1/im/channels/([0-9]+)/initiateSession but not sure if I could use it to include variables values.

Thanks