Please used below code for report template formate.
<?xml version="1.0" encoding="utf-8"?>
<odoo>
<data>
<template id="template_id">
<t t-call="report_layout">
<t t-foreach="docs" t-as="o">
<div class="page>
<table>
<thead>
<tr>
<th>Product name</th>
</tr>
<tr t-foreach="line" t-as="o.lines"> #"Add lines loops"
<tr>
<td><sapn t-field="line.product_id.name"/></td>
</tr>
</tr>
</table>
</div>
</t>
</t>
</template>
</data>
</odoo>