Blizzard have announced a "Welcome back" weekend this coming weekend until 7pm server time (CET) 21st November.
Anyone with an inactive account can log in and play for free during that time any content up to and including Shadowlands and the pre-expansion events (although unless they have Dragonflight expansion already, no Dracthyr available!).
Learn more about it here: https://worldofwarcraft.com/en-gb/news/23880880/join-the-welcome-back-weekend-17-20-november
Over the same weekend is a sale on Character services .. anyone wanting to transfer a character, or faction/name/race change can do so with a 30% discount. Visit the Blizzard store for more details.