I’ve had mixed experiences buying older model Vans shoes brand new in box, off eBay. Models/colorways as far back as 2012. Some held up as if I bought them from the store in present day. Others oxidized quickly and the glue began to fail. I don’t know if it had anything to do with storage, but I’d say just store them in a consistent climate that doesn’t go from humid to dry, cold to hot, hot to cold, etc. Same principle as boards, guitars, etc.