直接上代码啦

Cesium.Camera.DEFAULT_VIEW_RECTANGLE = Cesium.Rectangle.fromDegrees(90, -20, 110, 90);
const viewer = new Cesium.Viewer('cesiumContainer', {
selectionIndicator: false,infoBox: false,animation: false,baseLayerPicker: false,timeline: false,geocoder: false,homeButton: false,sceneModePicker: false,navigationHelpButton: false,orderIndependentTranslucency: false,contextOptions: {webgl: {alpha: true,preserveDrawingBuffer: true}},imageryProvider: new Cesium.UrlTemplateImageryProvider({url: '//www.google.cn/maps/vt?lyrs=s@726&x={x}&y={y}&z={z}',enablePickFeatures: false,maximumLevel: 20})
});

一键返回，官方文档

viewer.camera.flyHome(2);