I love old books; physical or digital, so for me two of the greatest things on the internet, are Project Gutenberg and the Read Era App on my phone.
With Read Era I can download books not only from Project Gutenberg but other sources as well.
I have used the app and Gutenberg for so many old classics for my grandchildren to read as part of their home-school assignments and for books of my own as well.
I recently got into reading an Agatha Christie novel that I happened to have on my Kindle so my first thought was to check Kindle for more of her novels. I quickly saw that most were not free. However on Gutenberg, they are ALL free. Same titles.
If you are not much of a reader, but still want to experience old classics, another great App is Librivox. With Librivox you can find a large assortment of old titles as audio books that you can download and listen to.
I have to say, I don’t know if either of these apps are on Apple phones but I do know they are on Android. I think if you like old classics, you will enjoy these apps.