Many MOOCs, whatever the subject area they cover, include learning activities which can help you develop your soft skills and digital soft skills.
Here are some examples of activities and the related skills. Of course these will also depend on the objectives of the activity itself and so may vary. But part of being a reflexive learner (and thus developing your learning-to-learn abilities) is asking yourself which (digital) soft skills the activity in question can help you develop.
So as you can see, even if the MOOC is on subjects such as mathematics, doping in sports or French 18th century literature, if you participate fully in the activities, especially those which require interaction with other learners, you will be developing a number of soft skills and digital soft skills.
For more information and definitions, see the section on soft skills.