Hey there, alysse272.
We understand that you're wanting to add specific workouts to the Health app with your iPhone SE (2nd generation), but not seeing those as an option.
Those workout types aren't available to add in the Health app itself. You could see if there are exercise apps from the App Store app that can share data with the Health app, which might have those workouts available. These articles may help:
In addition to that, if you are looking to select a specific workout type from your Apple Watch, you may consider the options discussed here: Workout types on Apple Watch. For example, for things like sit ups and crunches, that relates to the Core Training workout type. As quoted from this article, under the section titled, 'Add a workout', "Choose Other when you can't find a matching workout type. In all workouts, the Heart Rate and Motion sensors work together to give you accurate credit. When you use Other, or any workout type available in the Add Workout section, you earn the credit equivalent of a brisk walk when these sensor readings are unavailable."
Take care.