We have been given preloved items from family, like a bumbo seat, play centre, high chair etc. How do I best wash these to ensure they are sanitised and safe for a 6 month old with sensitive skin.

Red Nose does not have any specific information in relation to your question.

Maybe, use the same detergent that you wash your baby’s clothes in.
Don’t forget the old practice of “time in the sun”
You could also try wiping over with sanitizer (for sensitive skin) if you think it is suitable for your baby.