Most designer Clowns are very well taken care of. The ones I’ve bought in the past are fairly clear of most parasites because these breeders are very particular with their clowns. Now if they hit the fish store that’s a different story.
Either way... I’d start with feeding them Metroplex and put them through an observation period. Keeping good lighting on them to observe for any visual signs as well as odd behavior. If you have any maladies pop up, start treating them as they present unless you suspect Velvet, Brook, or Uronema. If that were the case, it would be a good idea to prophylactically treat starting at day 1. I always try to stay ahead of those 3.