In university lol, I didn't even know what software engineering was but I heard that there were good money working as something related so I choose it (I've always wanted to be an engineer but I didn't know )
I started in college and I think there's definitely something to the classroom learning and theory. For that you probably should look to online courses; I'm sure there's tons of them out there and many of them are probably free. That said, I probably learned more from actually writing code to achieve specific goals or solve problems. If you've got something you want to work on, getting a rudimentary baseline from a course or book and then tinkering with your project may be a better way to go if that syncs up with your learning style. Along the way, you'll nearly certainly do a bunch more reading, watching, and learning from other sources but it'll likely have more meaning (and be more enjoyable) if you're doing it for a particular purpose.