Within WordPress 4.6.1, when I go to edit a post, from the WYSIWYG editor, there is a drop-down option to apply multiple heading formats to the given text.
What is the WordPress way for developers to customize these heading options so that we can adjust the font size, color and font-family, for any one of these dropdown options? also can we add more options to the drop down?
Here is the link.
Now my little answer to your question in the comments: I can't guarantee that anything has changed since then. But I think it is a good base to start to do what you want to. And I can't remember big changes with tinyMCE in the last time.