best way to store or display books without have a book shelf
I use books as apart of my accessories. https://lifeonsummerhill.com/ There are loads of examples on my website. You can also stand them on end with bookends holding them up. And I saw another person who did wall art with books. https://www.instagram.com/p/Bt5t8yFFPkc/
Stacking them would be easiest.
Use them as decorative items throughout your room or home. You could stack a few of them and "belt" or tie a few together. Stack a few books to use as risers for other decorative item such as plants, clocks or decor pieces.
Concealed book mounts are one option.
And, last but not least, a Christmas Tree!
we have bookcases in all our rooms except bathrooms. Mostly built in bookcases which was one of the first things we made when we moved here in 1971. However thay are all different kinds, many of them "found" You can stack them on your steps, when we first were married we used metal strips from the hardware store that held brackets, that held wooden boards. Are you just looking for unique ideas or is there a special reason you do not want to use shelves?