https://www.xbox.com/en-US/games/store/ex-image-pulses-stratos-and-ghauri/9P467NLBJ1M2
Will be free for two weeks, will be paid on August 24th. You don't need to own the game to claim the DLC on Xbox.
Switch link (need a Switch to claim): https://www.nintendo.com/store/products/ex-image-pulses-stratos-and-ghauri-switch/