It sounds like you want to be able to access the fields of Model 1 from Model 3 through Model 2. To do this, you can use Odoo's relational fields.

For example, if you want to access the "name" field of Model 1 from Model 3, you can add a field to Model 3 like this:

name = fields.Char(related="model_2_id.model_1_id.name")

This will allow you to access the "name" field of Model 1 from Model 3 using the "name" field of Model 3. You can use this same technique to access any fields in Model 1 from Model 3, as long as they are accessible through the relationship between Model 2 and Model 1.

If you want to use this field in a domain filter, you can use the "name" field in the domain like this:

[('name', '=', 'some value')]

This will filter the records in Model 3 based on the value of the "name" field in Model 1.

I hope this helps! Let me know if you have any other questions.