how to update iPhone 5 to iOS 10.3.4?

If you're using an iPhone 5, run the Software Update function in General or update it from iTunes on a computer.

If you're using an iPhone 5c, it isn't subject to the GPS issue which 10.3.4 patches, so it's not needed or available for them. If you're trying to restore a backup created from 10.3.4, post back.

If you're using an iPhone 5s, update it to 12.4.3 as described for the iPhone 5.

If you're using an iPhone SE, update it to 13.2 as described for the iPhone 5.

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Your signature says you have a SE. The SE isn't affected and the latest version for the SE 13.2.