Want to plant some plumbago in other spots too, how to start new plants
It sounds like you are talking about the perennial groundcover plumbago, since the cape plumbago is not hardy in your zone 8. You can propagate by division and stem cuttings. These articles should help:
https://hgic.clemson.edu/factsheet/perennial-leadwort/
https://www.gardeningknowhow.com/garden-how-to/projects/rooting-plant-cuttings.htm