If you set up your intervals as a workout then each step with get recorded as a lap. If you want to be more accurate then run on a track and make the duration for the step as ‘until lap button press’ and manually lap with the bottom right button
HTH
I think the vast majority of people just use Auto Lap for mile or km splits. It would not make a lot of sense for instance to go out for a run for several hours and have auto laps going off say every 100 metres. If you did that with a marathon you would have over 400 auto laps. So there might a limit to avoid having activities with thousands of laps and probably causing all sorts of performance issues.