odoo16/addons/mass_mailing/wizard/mailing_mailing_schedule_date_views.xml

<?xml version="1.0"?>
<odoo>
    <record id="mailing_mailing_schedule_date_view_form"  model="ir.ui.view">
        <field name="name">mailing.mailing.schedule.date.view.form</field>
        <field name="model">mailing.mailing.schedule.date</field>
        <field name="arch" type="xml">
            <form string="Take Future Schedule Date">
                <group>
                    <group>
                        <field name="schedule_date" string="Send on" required="1"/>
                    </group>
                </group>
                <footer>
                    <button string="Schedule" name="action_schedule_date" type="object" class="btn-primary" data-hotkey="q"/>
                    <button string="Discard " class="btn-secondary" special="cancel" data-hotkey="z" />
                </footer>
            </form>
        </field>
    </record>

    <record id="mailing_mailing_schedule_date_action" model="ir.actions.act_window">
        <field name="name">When do you want to send your mailing?</field>
        <field name="res_model">mailing.mailing.schedule.date</field>
        <field name="type">ir.actions.act_window</field>
        <field name="view_mode">form</field>
        <field name="target">new</field>
    </record>
</odoo>