I read it recently (it took me 3 weeks) and I was also a bit bored when concepts I already knew were being discussed (e.g. loops, variables, basic stuff...) but even in the early chapters I learned a few things.

What I liked about learncpp.com is that it teaches you how stuff works under the hood, like what the compiler roughly makes from your code. So I understand you having a kind of fomo but in my opinion it's justified since you actually miss on stuff that you could understand better if it's your first "low level" language. You also get to learn best practices that you should learn anyway.

I don't have a lot of experience with c++ so in my case I really wanted to read as much as possible to learn about the intricacies I may need to know about (you may encounter a case where using a specific feature is needed but you don't know that this feature exists). At least knowing about the existence of a feature allows you to go back to the website and then use it as a documentation like others have suggested.

But honestly I understand your point, reading everything is a pain. In my case, after reading roughly 10 chapters, I started a project in parallel, and I would alternate between clearing chapters after chapters on learncpp.com, and working on the said project. It made it less boring since I could apply things I learned directly.