I created a custom Onboarding module using Odoo Studio.
When I add a Many2one field to link it with crm.lead, the field appears only in the form view, not in the model fields.
Therefore, the field does not show up in Automations (Link Field).
I’m using Odoo Online, so I cannot access Technical → Database Structure.
How can I force Studio to create a real Many2one field at the model level

Odoo Studio always creates fields in a Model and in Odoo Online you can access Technical -> Database Structure in developer mode. It's easy to create a filter to show all Studio fields and check them.