Is it possible to add a message(with a new subtype "Call") to the partner's/lead's chatter when a call status is changed to "Done"?

More generally, how to add a message to a model based on a condition in another model.

TIA

PS: I understand I could do it programmaticaly based on:

https://www.odoo.com/forum/how-to/developers-13/what-is-the-track-proprerty-of-mail-thread-model-used-for-1704

with

mail.message.subtype 

but how may I implement this on the SaaS?