After some extensive googling I was surprised to learn that there is no official ICS/CSV calendar exportable to, for example, Google calendar containing world events in WoW. (applicable to other games too.)
What I would like to see is some official API or otherwise publically available data as found on WoWhead → https://www.wowhead.com/events
After the long period of time WoW has been around with all of their staff and massive guilds looking to collaborate and plan their time accordingly I think it is due time to make this a feature.