iPhone owners can use the included Low Power Mode to save battery life on their iPhone in a pinch, and while it can be useful, I don’t particularly care for how it forces a 30-second auto-lock down your throat.
Apple doesn’t give you a way to increase the auto-lock timeout on a stock device with Low Power Mode enabled, but jailbreakers can take advantage of a free jailbreak tweak called NoLowPowerAutoLock by iOS developer SparkDev to command differently.