There’s a lot to C++ and it takes time to learn, especially if you don’t already know C and object-oriented programming.
I first learned C on the job back in the 80’s with the Kernighan and Ritchie book. Then I learned object-oriented programming by learning Ada on another job. After that, I got a job where I had to learn C++. I used the Stoustrup book for that. I never had formal classes in any of them.
There are bound to be better books now. I always have a hard time learning languages using only web resources.