In principle, yes. However, the Sony A6400 only has one UHS-I slot. In the Sony you will not be able to use the maximum speed of the card. On the PC you also need a UHS-II reader for the maximum speed. So a cheaper UHS-I card would also do.
Maybe you should also think about 2x 128GB instead of 1x 256GB.

SanDisk Extreme PRO SDXC (SDXC, 256 GB, U3, UHS-I)

https://www.alphashooters.com/cameras...

Hi claisse08,

yes, this memory card is compatible with the Alpha 6400 camera.

Sony Support EN