To add a new menu under the CRM module, you need to define the menu in XML using a custom module or through Odoo Studio. Here's how to do it with XML in a custom module: 

<odoo>

    <menuitem id="menu_crm_custom_root"

              name="Custom CRM Menu"

              parent="crm.crm_menu_root"

              sequence="100"/>

    <menuitem id="menu_crm_custom_submenu"

              name="My Submenu"

              parent="menu_crm_custom_root"

              action="action_custom_model"

              sequence="10"/>

</odoo>

If Using Odoo Studio:

1. Go to CRM > Studio.
2. Click on "Add Menu" at the top.
3. Choose the parent menu (CRM) and define your new menu name.
4. Link it to a model/view or create a new one.

Hi,

Refer to the following .

Video

- https://www.youtube.com/watch?v=mT43V3twcyE

- https://www.youtube.com/watch?v=vDQKIY163DM

Blogs

- https://www.cybrosys.com/blog/how-to-create-a-module-in-odoo-17

-https://www.cybrosys.com/slides/how-to-create-a-basic-module-in-odoo-17

- https://www.cybrosys.com/blog/how-to-define-menus-actions-in-odoo-17

Hope it helps

Hi 

First Create a module for this custom development, add the menu inside the CRM Module, create a model for these advanced options, and build the functionality you need inside that model's records.

Check these Tutorials 

Create Module in Odoo 17

Create Menu in Odoo 17

Regards