This is a good tutorial: https://decorbytheseashore.com/how-to-make-custom-closet-shelves/
Plastic crates stacked on top of each other for storing folded clothing.
Fix Brackets to wall and place timber on top. For a self supporting shelf rack, Use 4 pieces of timber and make two ladders that match each other. Held upright by the shelves, which will need to have a piece of timber fixed to each end on the underside to put over the ladder rails. Start at the bottom and work up. For stability add cross members on the back to line up with the ladder rungs.
Enjoy the journey........
I like using the melamine shelving available at home centers; the smooth surface makes the extra cost worthwhile. If you'd like something colorful, you can paint plain wood or cover with vinyl stick-on paper (I have some in a linen closet that have survived many years--it's a good thing it's a timeless design). There's always a selection of brackets to support the shelves, or you can use wood supports you make yourself from lumber.