Chosen Solution
Are there any sensors in the iPhone that indicate that the phone has been dropped that apple could use to tell me my warranty is void? I know they have moisture indicators, but never have heard of shock indicators.
Yes, they can tell that you dropped your phone I have just been to the apple store to run diagnostics on my iphone 5 and they told me thy i had dropped it 4 times, which was true. I never asked how they knew as i was worried that it might void warranty (but it didn’t because the dammage wasn’t directly because of dropping - it was a speaker problem not a cracked screen for example)
They can use the accelerometer logs from the phone itself to tell instantly. Also damage even subtle is noticeable on the inside of any apple device.
No there is not shock indicators in any iPhone Apple has made. It is too expensive to place that time of tech inside a device as small as an iPhone.