iPhone 6 plus screen.
iPhone 6 plus screen cracked on its own.
It's hard to imagine how high strength glass just breaks spontaneously. Regardless, nobody here can help you with physical damage to your phone. All you can do is take it in to Apple and see what they offer you in terms of repair or replacement, and don't be surprised if you have to pay for the repairs. Also, if you take it anywhere but Apple or an Apple Authorized repair center (find them on the Apple web site) to have it worked in, you will void all remaining warranty as well as any future possibility if out of warranty repairs.
If Apple repairs it, even if charged for out of warranty, that will re-instate your remaining warranty on the repaired device.