I have recently taken up this matter again. I have reviewed the crm.lead model and I have found the company_id field. Although I was surprised when I did not find the rule that uses the said field. For instance, in the case of res.partner we have the rule "res.partner company"

Edited.

Fabrice Henrion sais on \this link https://www.linkedin.com/groups/165657/165657-6249547340802195456 "Odoo CRM is multi-company. Just create a record rule on the company_id field of the crm.lead model (if that's what you are trying to achieve). 5 minutes of work."

Thanks you very much