Currently there's no direct way to do it, I think. But you can get this done in 1-2 mins.
What you have to do is:
- make a copy of your model / workspace just to be sure
- create the lines you want to cut them along
- turn those lines into a planar face
- from the planar phase, exture a cube
- tap on the number icon and set it to "Intersect"
This will give you only the parts that is intersecting with the iPad Pro case + the cube you just created.
Also, what you can do is to have your ipad pro case model open. Place 4 big cubes that are touching and overlapping with the model. And use the Intersect tool to cut it into pieces. It can be done in a few seconds literally, 1-2 mins max.
I can do a video on how to do it, if you need it.