odoo18/addons/web/static/src/webclient/webclient.xml

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

    <t t-name="web.WebClient">
        <t t-if="!state.fullscreen">
            <NavBar/>
        </t>
        <ActionContainer/>
        <MainComponentsContainer/>
    </t>

</templates>