Вы можете использовать многоугольную директиву
<agm-map [latitude]="lat" [longitude]="lng" [zoom]="zoom">
<agm-polyline>
<agm-polyline-point *ngFor="let point of arcPoints" [latitude]="point.latitude" [longitude]="point.longitude">
</agm-polyline-point>
</agm-polyline>
</agm-map>
и в component.ts
ngOnInit() {
this.arcPoints = drawArc(center, initialBearing, finalBearing, radius);
}