social/mail_activity_crm/views/crm_lead_views.xml

<?xml version="1.0"?>
<odoo>
    <!--
        Copyright 2016 Odoo SA <https://www.odoo.com>
        Copyright 2018 Therp BV <http://therp.nl>
        Copyright 2018 Eficent <http://www.eficent.com>
        License LGPL-3.0 or later (http://www.gnu.org/licenses/lgpl.html).
    -->
    <record model="ir.ui.view" id="crm_case_kanban_view_leads">
        <field name="name">CRM - Leads Kanban</field>
        <field name="model">crm.lead</field>
        <field name="inherit_id" ref="crm.crm_case_kanban_view_leads"/>
        <field name="arch" type="xml">
            <field name="message_needaction_counter" position="after">
                <field name="activity_ids"/>
                <field name="nbr_activities"/>
            </field>
             <xpath expr="//div[@class='oe_kanban_content']" position="inside">
                 Next activity:
                <div class="text-muted">
                    <t t-if="record.activity_date_deadline.raw_value and record.activity_date_deadline.raw_value lt (new Date())" t-set="red">oe_kanban_text_red</t>
                    <span t-attf-class="#{red || ''}">
                        <field name="activity_date_deadline"/>
                        <t t-if="record.activity_date_deadline.raw_value"> : </t>
                        <field name="activity_summary"/>
                    </span>
                </div>
                <div t-if="record.nbr_activities.raw_value">
                    <field name="activity_ids" widget="kanban_activity"/>
                </div>
            </xpath>
        </field>
    </record>
    <record model="ir.ui.view" id="crm_case_form_view_leads">
        <field name="name">CRM - Leads Form</field>
        <field name="model">crm.lead</field>
        <field name="inherit_id" ref="crm.crm_case_form_view_leads" />
        <field name="arch" type="xml">
            <xpath expr="//div[@class='oe_chatter']/field[@name='message_follower_ids']" position="after">
                <field name="activity_ids" widget="mail_activity" />
            </xpath>
        </field>
    </record>

    <record model="ir.ui.view" id="crm_case_form_view_oppor">
        <field name="name">Opportunities</field>
        <field name="model">crm.lead</field>
        <field name="inherit_id" ref="crm.crm_case_form_view_oppor" />
        <field name="arch" type="xml">
            <xpath expr="//div[@class='oe_chatter']/field[@name='message_follower_ids']" position="after">
                <field name="activity_ids" widget="mail_activity" />
            </xpath>
            <xpath expr="//sheet/group/group[2]/label" position="attributes">
                <attribute name="invisible">True</attribute>
            </xpath>
            <xpath expr="//sheet/group/group[2]/div" position="attributes">
                <attribute name="invisible">True</attribute>
            </xpath>
        </field>
    </record>
</odoo>