Excellent question!!! Here is the feature request, that has been pushed off for a few years. https://gitlab.kitware.com/paraview/paraview/issues/15810. It comes from uservoice, here: https://paraview.uservoice.com/forums/11350-general/suggestions/1350851-create-the-ability-to-automatically-label-contour.
I’m pretty sure this will slip. There just isn’t time to get it into the spring release, and the fall release will be a smaller release, trying to get back on schedule. After that, this feature is towards the top of the queue.