the default size for a SimpleRow with only a text is dp(42) on iOS and dp(48) on Android. With detailText and image the size is dynamic, depending on the content. We already discuss setting up a doc page with those constants, as they can be quite handy to have some values to base custom layouts on.
this is hard to say, as it is really dynamic depending on the content. On iOS it would roughly equal to dp(59), but not pixel perfect. On desktop the size can be different for iOS theme selected, as the font will be different, and thus the actual height of the text items. What’s your exact use case? If you make a custom row that should look native on mobile, you can aim for around dp(60) in height.