pos/pos_cashier_login/views/pos_config.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright (C) 2019 by Lambda IS <https://www.lambda-is.com> -->
<odoo>

    <record id="view_pos_config_form" model="ir.ui.view">
        <field name="model">pos.config</field>
        <field name="inherit_id" ref="point_of_sale.pos_config_view_form" />
        <field name="arch" type="xml">
            <xpath expr="//div[@id='barcode_scanner']" position="after">
                <div class="col-xs-12 col-md-6 o_setting_box">
                    <div class="o_setting_left_pane">
                        <field name="require_cashier_login"/>
                    </div>
                    <div class="o_setting_right_pane">
                        <label for="require_cashier_login" string="Cashier Login"/>
                        <div class="text-muted">
                            Require that the cashier is set (or scanned) before each new order.
                        </div>
                    </div>
                </div>
            </xpath>
        </field>
    </record>

</odoo>