Update iPhone5 (ME356LL/A) to iOS 10.3.4

I have a iPhone 5s. It currently have iOS 9.3.5. I have read that it needs updating to 10.3.4, Software update on the phone lists iOS 10.2.1. This 10.2.1 version won't install. The phone "waits".

Connecting to iTunes on my Mac wants to update it to iOS 13, which I do not want to do at this time.

Any ideas? Thanks ahead of time.