I came across a third-party plugin that was able to add "tabs" to the post block-editor page of a certain custom post type. I cannot figure out how this was done. Moreover, I would like to know whether it is possible to "filter" these tabs. Each of these "tabs" contains a bunch of metaboxes of sorts. Since I have other people running the site with me, how can I have them be able to "access" the first "Lesson page" tab but not the second "Settings" tab, based on user role of course.
I tried to go through the source code of the 3rd-party plugin and use and relevant filter hooks to remove the metaboxes of the "Settings" page but to no avail. I temporarily hid the unwanted tabs using CSS, but this is obviously crooky and insecure.