Hello HANT,

For that, You want to inherit existing report and add your own fields.

Try below code :-

<?xml version="1.0" encoding="utf-8"?>
<odoo>
<data>

<template id="account_invoice_report_add_field" inherit_id="account.report_invoice_document">
    <xpath expr="//span[@t-if='o.partner_id.vat']" position="before">
        Ice : <t t-field="o.partner_id.ice"/>
    </xpath>
</template>

</data>
</odoo>

Hope it will works for you.

Thanks,