pos/pos_tare/views/view_pos_order.xml

<?xml version="1.0"?>


<odoo>

    <record model="ir.ui.view" id="view_pos_order_form">
        <field name="model">pos.order</field>
        <field name="inherit_id" ref="point_of_sale.view_pos_pos_form"/>
        <field name="arch" type="xml">
            <field name="qty" position="after">
                <field name="tare"/>
            </field>
        </field>
    </record>

</odoo>