is there a way to smooth the corners on a polyline drawn with react-native-maps?

My code looks like this:

const coords = {//...etc}

<MapView.Polyline
    key="LTrainPolyline"
    coordinates={coords}
    strokeColor="grey"
    strokeWidth={1}
/>

There is a lineJoin prop but I cannot figure out how to use it and the documentation is minimal. I want to turn a corner like this: V => U. I have a feeling Im trying to avoid going in and manually adding a whole bunch of coordinates to simulate a curve.