Hi,

In order to modify the quotation form view or any other views in Odoo, you can just inherit that view and can add the desired changes to the view.
For example, for modifying the sales view, you can add this xml code in your xml file and add it in module manifest.

<record id="view_order_form_inherit_example" model="ir.ui.view">

               <field name="name">sale.order.form.inherit.example</field>

              <field name="model">sale.order</field>

              <field name="inherit_id" ref="sale.view_order_form"/>

              <field name="arch" type="xml">

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

                            <field name="custom_field_name"/>

                      </xpath>

                </field>

          </record>

Regards