Hii,

Create or Use a Custom Module

If you don’t already have one, create a custom module called (for example) custom_website_header.

Folder structure:

custom_website_header/
├── __init__.py
├── __manifest__.py
├── static/
│   └── src/
│       └── css/
│           └── header.css
├── views/
│   └── header_template.xml

Inherit the Header Template

Odoo uses website.layout → website.header for the main header.

Here’s how to extend or replace part of the header in views/header_template.xml:

<?xml version="1.0" encoding="UTF-8"?>
<odoo>
  <template id="custom_website_header" inherit_id="website.header" priority="20">
    <!-- Example: Replace social media icons section -->
    <xpath expr="//div[contains(@class, 'o_header_social')]"
           position="replace">
      <div class="o_header_social">
        <!-- Add your own icons or links here -->
        <a href="https://facebook.com" target="_blank">FB</a>
        <a href="https://linkedin.com" target="_blank">LinkedIn</a>
        <a href="https://instagram.com" target="_blank">Insta</a>
      </div>
    </xpath>

    <!-- Example: Add a phone number above the menu -->
    <xpath expr="//header" position="inside">
      <div class="my-top-bar text-center py-1 bg-warning text-dark">
        <span>📞 +971 525585292 | ✉️ yahyasbini@gmail.com</span>
      </div>
    </xpath>
  </template>
</odoo>

changes as your requiremnts

Add Custom CSS 

Create static/src/css/header.css and style your changes:

.my-top-bar {
    font-weight: bold;
    font-size: 14px;
}

.o_header_social a {
    margin: 0 8px;
    color: #fff;
}

add css as per your design

update __manifest__.py

{
    'name': 'Custom Website Header',
    'category': 'Website',
    'version': '16.0.1.0.0',
    'depends': ['website'],
    'data': [
        'views/header_template.xml',
    ],
    'assets': {
        'web.assets_frontend': [
            'custom_website_header/static/src/css/header.css',
        ],
    },
    'installable': True,
}

i hope it is use full