Hi,

Try refer following code.

<t t-name="ClientListScreen" t-inherit="point_of_sale.PartnerListScreen" t-inherit-mode="extension" owl="1">
   <xpath expr="//table[hasclass('partner-list')]//th[last()]" position="after"> 
      <th>Customer Tags</th>
   </xpath>
</t>
<t t-name="ClientLine" t-inherit="point_of_sale.PartnerLine" t-inherit-mode="extension" owl="1">
    <xpath expr="//tr/td[last()]" position="after">
        <td class="text-center">
           <center>
            <t t-esc="props.partner.category_id.name" />
           </center>
        </td>
    </xpath>
</t>

Regards