Taking advantage of the multiple lockdowns, I began to re-read the classics I had read in the 80s and 90s. Take my advice: don't do that. You will be terribly disappointed.
First point: half of those novels would not pass a a patient slush reader at a modern publisher: heavy style, lengthy paragraphs (can you imagine the beginning of the Lord of the Rings?), Atrocious clichés (Legend by David Gemmell where Rek leaves for a trip of several days in a snowy forest without clothes or even food for him and what about his horse?). Multiple parts written in tell (a good part of The Left Hand of Darkness by Ursula Le Guin). Digressions and flat and empty dialogues (The Witcher by Andrzej Sapkowski). Nowadays, these classics would hardly find a publisher or an audience.
Second point: many of them were a product of their time and it would be awkward to make them say more than they meant in their original context. Nowadays, we think the Left Hand of Darkness is brilliantly questioning gender. Except that almost all the characters of the book are called "he", even in their "female" form. The rare times they find themselves in a "feminine" situation, terrible things happen to them: a character has his head bashed to death by his spouse. The king (no, not the queen) gives birth to a stillborn child and loses what is left of his (her?) sanity. Estraven is shot dead. Finally, the main ingredient in the divination system is the frustrated sexual desire of a "male" for "a" "female" (it is referred to as "he" in the text). In short, if this novel were released today from a "gender questioning" perspective, it would have been heavily criticized.
Third point: some novels have managed to age well. I read with pleasure Dune by Franck Herbert, Planet of Adventure by Jack Vance and Deathworld by Harry Harrison. How did they do that?