Phew!
Depends on what type of sarcoid; where it’s sited and what this growth affects; how large; whether it is growing / weeping / bleeding; how old and otherwise healthy the horse is; which type of treatment is being considered; whether there is veterinary insurance / sufficient funds…..
As long as a piece of string and potentially just as knotty!
Supporting the horse’s immune system is always a sensible idea, whatever else you do / don’t do about the sarcoid.