Hi,

1)Inside heirarchy_details.py file provide the code

from odoo import fields, models


class DepartmentDetails(models.Model):
    _name = 'department.details'
    _description = 'create a new model for hierarchy'
    _rec_name = 'department'

    department = fields.Char()
parent_id = fields.Many2one("department.details")
child_ids = fields.One2many("department.details", 'parent_id')

Note : give heirarchy_details.py file in your __init__ file

2) in the security file give :

id,name,model_id:id,group_id:id,perm_read,perm_write,perm_create,perm_unlink
heirarchy_view.access_department_details,access_department_details,heirarchy_view.model_department_details,base.group_user,1,1,1,1

3) In the heirarchy_menus.xml file provide:

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <menuitem id="heirarchy_manager_menu"
              name="License Manager"
              sequence="0"/>
    <menuitem id="heirarchy_list_menu"
              name="Heirarchy List"
parent="heirarchy_manager_menu"
              action="heirarchy_list_action"
              sequence="0"/>
</odoo>

4)In heirarchy_views.xml file provide

<?xml version="1.0" encoding="utf-8"?>
<odoo>
<record id="view_department_details_tree" model="ir.ui.view">
<field name="name">view.department.details.tree</field>
<field name="model">department.details</field>
        <field name="arch" type="xml">
            <tree>
                <field name="department"/>
                <field name="parent_id"/>
                <field name="child_ids"/>
            </tree>
        </field>
    </record>
<record id="view_department_details_form" model="ir.ui.view">
<field name="name">view.department.details.form</field>
<field name="model">department.details</field>
        <field name="arch" type="xml">
            <form>
                <sheet>
                    <group>
                        <field name="department"/>
                        <field name="parent_id"/>
                        <field name="child_ids"/>
                    </group>
                </sheet>
            </form>
        </field>
    </record>

<record id="department_details_view_hierarchy" model="ir.ui.view">
<field name="name">department.details.view.hierarchy</field>
<field name="model">department.details</field>
        <field name="arch" type="xml">
            <hierarchy child_field="child_ids"
                       draggable="1">
                <field name="department"/>
                <templates>
                    <t t-name="hierarchy-box">
<div t-attf-class="o_hierarchy_node_header d-flex justify-content-center pb-4"
                             t-att-title="parent_id">
                        </div>
                        <div class="o_hierarchy_node_body d-flex flex-column text-center">
                            <div class="w-100 position-relative">
                                <field class="fw-bold" name="department"/>
                                <br/>
                            </div>
                        </div>
                    </t>
                </templates>
            </hierarchy>
        </field>
    </record>
    <record id="heirarchy_list_action" model="ir.actions.act_window">
        <field name="name">Department Manager</field>
<field name="type">ir.actions.act_window</field>
<field name="res_model">department.details</field>
<field name="view_mode">tree,form,hierarchy</field>
        <field name="help" type="html">
<p class="o_view_nocontent_smiling_face">
                No data yet!
            </p>
            <p>Create department Records.
            </p>
        </field>
    </record>
</odoo>

Note:

 Add your models directory in your main __init__ file, also configure your __manifest__ file.

If you done all the above steps properly , then the output will be like:

Hope it helps