Add water outline to my "light" mapbox map - mapbox

Question

I see that some maps styles use a layer called "water outline." You can see this layer in this pic as the blue outline next to the water.
I am using the light-v9 style from mapbox and am wondering how to "import" this layer onto my map so that I can have water outlines, too.
Here is how I set my map:
var map = new mapboxgl.Map({
container: this.mapContainer,
style: 'mapbox://styles/mapbox/light-v9',
interactive: true,
maxZoom: 16,
});
And this is how I make a couple style changes:
map.on('load', function () {
map.setPaintProperty('background','background-color', 'rgb(246, 246, 246)')
map.setPaintProperty('parks','fill-color', 'rgb(217, 232, 222)')
map.setPaintProperty('water','fill-color', 'rgb(224, 230, 230)')
...
})

Answer 1

It looks like that layer comes from the Mapbox Streets v7 vector tiles. If you would like to create a new line layer from that source, you would want to query the map's source for the water layer, then use it to create a line layer. For example:
map.addLayer({
'id': 'water-line-layer',
'source': 'composite',
'source-layer': 'water',
'type': 'line',
'minzoom': 15,
'paint': {
'line-color': '#000000',
'line-width': 10
}
}