I'd recommend watching the behind the scenes documentaries. All 3 movies combined, it's 9 hours of footage, and it's compelling and well made. Half the marvel of the movies is seeing all that they accomplished when making them. It was especially impressive 20 years ago when it was shattering everyone's expectations.
It's easier to get invested in the movies if you know more about the books, the art design, the actors, the lore, the extreme attention to detail. It's a decent substitute for reading the books since it explains a decent chunk of the backstory and discusses the script adaptations and has interviews with Tolkien experts as well.