One way would be to have an accelerometer detect that the phone is falling, and have tiny spring-actuated bumpers, wires, or feet extend from the corners of the phone to catch its fall. Little stainless-steel or Nitinol wires would do great.
Back when the early iPods actually contained a spinning hard drive, they had something similar. If it detected a fall, it would quickly park the hard drive to avoid damage.
Here's a patent for the idea which just expired this year: https://patents.google.com/patent/US7059182B1/
Apple also patented some versions of this, although I think not as nice as the 2005 one: https://patents.google.com/patent/US9571150B2