Hi,

Please try following code,
Models → .py file

from odoo import models, fields


class Level(models.Model):
    _name = 'gc.level'
    name = fields.Char(string='Degree', required=True)
    note = fields.Integer(string="Note", required=True)
    description = fields.Text(string="Description")
    critere_id = fields.Many2one('gc.criteria', string="Criteria")


class Criteria(models.Model):
    _name = 'gc.criteria'
    name = fields.Char(string='Critère')
    levels_ids = fields.One2many('gc.level', 'critere_id', string="Degree")

Views → .xml file

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <data>
        <record id="view_gc_criteria_form" model="ir.ui.view">
            <field name="name">gc.criteria.form</field>
            <field name="model">gc.criteria</field>
            <field name="arch" type="xml">
                <form>
                    <sheet>
                        <field name="name"/>
                        <div>
                            <group>
                                <field name="levels_ids">
                                    <field name="name"/>
                                    <field name="note"/>
                                    <field name="description"/>
                                    <field name="critere_id" invisible="1"/>
                                </field>
                            </group>
                        </div>
                    </sheet>
                </form>
            </field>
        </record>
        <record id="gc_criteria_tree_view" model="ir.ui.view">
            <field name="name">gc.criteria.tree</field>
            <field name="model">gc.criteria</field>
            <field eval="8" name="priority"/>
            <field name="arch" type="xml">
                <tree string="Test Email">
                    <field name="name" string="Reference"/>
                    <field name="levels_ids"/>
                </tree>
            </field>
        </record>
        <record id="action_gc_criteria_form" model="ir.actions.act_window">
            <field name="name">Gc Criteria</field>
            <field name="res_model">gc.criteria</field>
            <field name="view_mode">tree,kanban,form</field>
        </record>
        <menuitem action="action_gc_criteria_form" name="Gc Criteria"
                  id="menu_action_gc_criteria" string="Gc Criteria" parent="parent_module.menu_id" sequence="4"/>
    </data>
</odoo>

Security → .csv file

id,name,model_id:id,group_id:id,perm_read,perm_write,perm_create,perm_unlink
access_gc_criteria,test_email.gc_criteria,model_gc_criteria,base.group_user,1,1,1,1
access_gc_level,test_email.gc_level,model_gc_level,base.group_user,1,1,1,1

Regards