Update an iPhone 5c to iOS 11

iPhone 5c can't be updated past 10.3.3. iOS 11 or 12 isn't supported by 5c because of insufficient hardware and lack of 64-bit architecture.

And no, 10.3.4 wasn't released for the 5c, because the 5c isn't affected by this GPS bug.

https://support.apple.com/en-us/HT201222

iOS 10.3.4: iPhone 5, iPad (4th generation) Wi-Fi + Cellular

No.

(173512)

You can update to iOS 10.3.4 released on July 22, 2019; 17 days ago

Not iOS 11