[iOS 13] Health app: getting steps in km

If you are in Summary, select Show All Health Data. Once that is displayed, go to Walking and Running Distance. Scroll down to the bottom of the page, you should see a section under Options, and that has a setting marked, Unit. Tap on that and you can select km, or mi.

It would be better if you can please post a screenshot of your iPhone's Activity data, in order to understand the phenomenon better.

I have iPhone SE with iOS 13.2

I still get it in Miles (See the pic below)