My current iron has a self cleaning cycle that blows that crud mostly out!
With previous irons I’ve loosened the crud up and then yes, I’ve used vinegar. After a vinegar cycle I’d run a cycle with water. It’s worked pretty well, but I don’t mind vinegar and use it to clean lots of things.
I believe there is a specific iron cleaning solution sold for this, but my iron isn’t so expensive that I e felt the need to use anything more expensive than vinegar.