Try this.

<record id="custom_invoice_form" model="ir.ui.view">
 	<field name="name">account.invoice.custom</field>
 	<field name="model">account.invoice</field>
 	<field name="inherit_id" ref="account.invoice_form" />
 	<field name="arch" type="xml">
 		<xpath expr="//field[@name='partner_id']" position="after">
                    <field name="insert_your_field_here" />
 		</xpath>
 	</field>
 </record>

https://kanakinfosystems.com/blog/how-to-customize-a-report-in-odoo

https://www.cybrosys.com/blog/modifying-existing-qweb-reports-in-odoo13