Your NIPT already places you in the low risk group, and the anomaly scan at 18 to 20 weeks is routine for every pregnancy, not something extra you need because of one marker.
Next Steps
Mention the chromosome 13 value to your obstetrician at your next visit so they can decide if anything specific applies to you.
Health Tips
A single number within range rarely changes your plan, but only your own doctor can confirm that for you.