How do I place my layer list in a expand in arcgis javascript api?

I am creating an application using arcgis javascript api. I placed my basemap gallery in an expand and I would like to do the same with my layer list. How do I add my layerlist to an expand?.

This is how I did my basemap gallery:

const basemapGallery = new BasemapGallery({
    view: view,
});

// Create an Expand instance and set the content
// property to the DOM node of the basemap gallery widget
// Use an Esri icon font to represent the content inside
// of the Expand widget
const bgExpand = new Expand({
    view: view,
    content: basemapGallery
});

// close the expand whenever a basemap is selected
basemapGallery.watch("activeBasemap", () => {
    const mobileSize = view.heightBreakpoint === "xsmall" || view.widthBreakpoint === "xsmall";
    if (mobileSize) {
        bgExpand.collapse();
    }
});

// Add the expand instance to the ui
view.ui.add(bgExpand, "top-left");

Solution

Is exactly the same as you did with the basemap gallery, in this case the content will be the layer list.

In the code below I slightly change and ESRI layer list example (ArcGIS JS Samples - LayerList) it to include the expand.

<html lang="en">

<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="initial-scale=1, maximum-scale=1,user-scalable=no" />
    <title>
        LayerList widget | Sample | ArcGIS Maps SDK for JavaScript 4.26
    </title>

    <link rel="stylesheet" href="https://js.arcgis.com/4.26/esri/themes/light/main.css" />

    <style>
        html,
        body,
        #viewDiv {
            padding: 0;
            margin: 0;
            height: 100%;
            width: 100%;
            overflow: hidden;
        }
    </style>

    <script src="https://js.arcgis.com/4.26/"></script>

    <script>
        require([
            "esri/views/SceneView",
            "esri/widgets/LayerList",
            "esri/WebScene",
            "esri/widgets/Expand"
        ], (SceneView, LayerList, WebScene, Expand) => {
            const scene = new WebScene({
                portalItem: {
                    // autocasts as new PortalItem()
                    id: "adfad6ee6c6043238ea64e121bb6429a"
                }
            });

            const view = new SceneView({
                container: "viewDiv",
                map: scene
            });

            view.when(() => {
                const layerList = new LayerList({
                    view: view
                });
                const expand = new Expand({
                    view: view,
                    content: layerList
                });

                // Add widget to the top right corner of the view
                view.ui.add(expand, "top-right");
            });
        });
    </script>
</head>

<body class="calcite">
    <div id="viewDiv"></div>
</body>

</html>