Is Life is Strange: Before the Storm optimized for Retina displays?

Yes.

If you have a Retina display, you will be able to take advantage of the extra pixels by running Life is Strange: Before the Storm in native resolution. This means that the game will display one pixel for every pixel on your display.

You can change the game's resolution within the game under Settings → Video settings, accessible from the Main Menu.

NOTE: In many cases, increasing your game's resolution will impact upon its performance. For tips on improving performance, read the Performance Tips point in the ReadMe.