This is essential for anyone writing shorter pieces or submitting copy for a column etc. Also for planners who are working to a strict outline.
But many ways it can be done, and targets might be for a group of notes.
Analytics is useful. ProWritingAid works happily, and fast, with markdown files if you have it installed. Not free of course but can be cheap in one of their frequent sales. Easy to set up to work on any given folder.
External editors bring many of these features and can be triggered within Obsidian. Not many specialist writing programs work with markdown yet though. But won’t be long, I’m sure.