What does the iOS 13.5.1 update do?

iOS updates enhance security, repair defects, and occasionally add new features.

About iOS 13 Updates - Apple Support

lbruski43 wrote:

Only the Covid 19 tracing update. No other significant items.

That’s actually incorrect in both assertions.

The Covid 19 tracing update was supplied in an earlier release.

And again, iOS 13.5.1 provides significant security enhancements.

Only the Covid 19 tracing update. No other significant items.