SOURCE

var coordList = [
    [
        [
        118.544694359,
        29.394588189000004
        ],
        [
        118.542326689,
        29.336553810999973
        ],
        [
        118.48461473699999,
        29.363640637000017
        ],
        [
        118.544694359,
        29.394588189000004
        ]
    ]
]

var polygon = new ol.geom.Polygon(coordList);

var vectorLayer = new ol.layer.Vector({
    source: new ol.source.Vector({
        features: [
            new ol.Feature(polygon)
        ]
    })
});
const source = new ol.source.OSM();

// 鹰眼控件
var controls = new ol.control.defaults().extend([
    new ol.control.OverviewMap({
        rotateWithView: true,
        tipLabel: '123',
        layers: [
            new ol.layer.Tile({
                source
            }),
            vectorLayer
        ]
    })
])

var map = new ol.Map({
    target: 'map',
    controls, 
    layers: [
        new ol.layer.Tile({
            source
        }),
        vectorLayer
    ],
    view: new ol.View({
        projection: 'EPSG:4326',
        center: [118.542026689, 29.364503810999973],
        zoom:10
    })
});

<div id="map" class="map"></div>

.map {
    height: 550px;
    width: 100%;
}