https://experience.sap.com/fiori-design-web/full-screen/
Simply add appWidthLimited:false in your index.html
<script>
sap.ui.getCore().attachInit(function() {
new sap.m.Shell({
appWidthLimited:false,
app: new sap.ui.core.ComponentContainer({
height : "100%",
name : "my.demo.app"
})
}).placeAt("content");
);
});
</script>
