The release of the new add-on for Hearts of Iron 4 was announced some time ago. We already have the opportunity to buy the DLC in pre-order, and we also know the release date of the add-on. The Hearts of Iron IV: Arms Against Tyranny DLC will be released on October 10, 2023.
Pre-order bonus
There will be a special reward for those who decide to purchase the DLC in advance – a music track Säkkijärven Polkka that will be available in the game.
Sources:
https://www.paradoxinteractive.com/games/hearts-of-iron-iv/add-ons/hearts-of-iron-iv-arms-against-tyran