Hi,

You can override the create method of the model A and then calling create function of the model B you can create the record.

Sample:

class Model_A(models.Model):
    _inherit = 'model.a'
    
    @api.model
    def create(self, values):
        res = super(Model_A, self).create(values)
        vals = {
            'field_1': 'test',
            'field_2': 'test'
        }
        self.env['model_b'].create(vals)
        return res

Thanks