When you launch the game, now, Steam will ask you which launch option you want to use:
Which option should I pick?
There are two options to pick from...
DirectX 12 (Default)
Vulkan
DirectX 12 is the game's default option. However, if you experience freezes or crashes while playing, you might want to give the Vulkan version a try!
Freezes and crashes could point to troubles with graphics hardware/drivers support: Which is why switching the game's graphics API (Direct X12 or Vulkan) might help—on most setups with modern hardware, there should be virtually no difference between both versions.
If you have found an option that works fine for you, simply tick the checkbox for "Always use this option"!