I learnt Lightroom mostly from books I borrowed from the library, and trying out techniques from various online sites... I read Scott Kelby's book, others also recommend the one by Martin Evening and Adobe Classroom in a Book series.
Yeah, have your tried the Youtube tutorials? Frankly, I've never learned any software from a course, and I'd venture to say many pro and enthusiast photographers are the same. From the 80s to the 00s, it was 3rd party books and magazines, now Youtube, for learning everything from QuarkXpress to Flash, Photoshop to Lightroom. There are many excellent Youtube tutorials out there that teach the basics to specific advanced techniques.
I never learn the software features by rote. For example, I'm learning Da Vinci Resolve now, and when I wanted to have some captions move to follow an object, I searched Youtube, and there were several free step-by-step tutorials, and you can follow along for better retention (I think they call this micro-learning now)
Youtube can be chaotic but there are structured courses if you like that.
Otherwise online learning platforms works out well too. One example which I used previously was lynda. I have also bought the ebooks for my camera from Gary Friedman. That helped me a lot.
Another one which seems interesting but I haven't tried out would be the one from youtube channel but they have the structured course at sdp.io
Their free lightroom guides on youtube are pretty good so I assume the paid for course would be pretty good as well. Lightroom is a very simple program compared to photoshop so once you have your workflow in place you pretty much stick to it if you take a lot of pictures.