Do silicone sex dolls need powdering?

No. Powdering with talc or cornstarch is a TPE routine — it absorbs the oil that TPE gradually releases and keeps the surface from turning tacky. Silicone does not release oil and does not become tacky, so powder has nothing to do and simply builds up in the seams and joints. The same applies to conditioning and mineral oils: they are TPE maintenance and on silicone they only leave residue. Wash, dry thoroughly, store correctly, and that is the whole routine.