Navigate to Settings, then Technical.

From the User Interfaces dropdown, select Views.

Click the New button.

Enter the Name: Custom Quotation List with Customer Ref

Set the View Type to: List

Set the Model of the view to: Sale Order

Set the Inherited View to: sale.order.tree

Set the View Inherited Model to: base View

Set the Sequence to: 16

Toggle Active to Green.

In the Architecture editor, input the following code:

<xpath expr="//field[@name='name']" position="after">

<field name="client_order_ref" optional="hide"/>

</xpath>

The form should now appear as shown.

Subsequently, return to the Quotations and select Customer Reference from the list by clicking on the three dots.

Hope It will help, Happy Odoo John!