For a while already people were recommending to use regular Notes app but that just does not always work.
Method #1: The Return
All you have to do it hit return after the full stop and you’ll line break. There can be no characters after the full stop (period), not even a space, just the hard return.
You can even skip down twice that way, as long as there is nothing after the full stop.
Method #2: Use an app
Use apps like Line Break Generator or Line Breaks.