You can learn so much right here on the platform, but I did buy Ayodeji Awosika course and though I still haven't worked through it all, it was absolutley worth it.
You get lifetime access and he does regular coaching sessions and get feedback and input on articles. 2 main things have really helped me the most so far
1) Headline structure. I know you can learn how to write good headlines right here on the platform he has a vault of killer headlines that you can adapt to use to your own writing.
2) fine tuning your writing process. One simple tip he shared has helped me to speed up my writing. I'm still working on this as it does take me a really long time to create and then edit an article, but the tips he gives have helped me to really iron out my writing process. and working on getting more out of my writing time.
I'm not even 1/2 way through it as I want to prioritise my writing first and formost, but I would certainly say it's been worth the investment if for just these 2 things, and I think his course (I can't vouch for any others) is about impriving your skill as a writer. And to be able to write anywhere and not just for Medium.
That's just my experiences. You just got me thinking. I should probably turn this review into an article myself lol.