odoo-tutorials/awesome_dashboard/static/src/dashboard.xml

<?xml version="1.0" encoding="UTF-8" ?>
<templates xml:space="preserve">

    <t t-name="awesome_dashboard.AwesomeDashboard">
        <Layout display="display" className="'o_dashboard h-100'">
            <t t-set-slot="layout-buttons">
                <button class="btn btn-primary" t-on-click="openCustomers">Customers</button>
                <button class="btn btn-primary" t-on-click="openLeads">Leads</button>
            </t>
            <div class="d-flex flex-wrap">
                <DashboardItem />
                <DashboardItem size="2">That's a bigger one</DashboardItem>
                <DashboardItem/>
            </div>
        </Layout>
    </t>

</templates>