This is precisely what Mortimer Adler suggests in his book "How to Read a Book", to read above your current levels this is only how you grow your mind.

Strong advice but I feel it's much harder nowadays to go down that route when there are distractions like YouTube videos that are easy to watch and make you feel you're learning when really it's scratching a superficial curiosity itch with no depth.

That said, to answer OP's question, I got Mortimer's book called "Great Treasury of Western Thought" that has compiled quotes from Western classics into key themes (the human condition, love, religions, etc), and it provided the missing link between getting meaty samples of key concepts, versus actually reading ALL the classics (the book started as the the index or 'syntopicon' of the 'Great Books of the Western World', a full compilation of Western works)