As a Kallax enjoyer I used to hate that I was limited to ~32cm width and height, it took me years to realize that I can just remove some of the dividers and make the nooks either wider or taller if I rotate (!) the shelf. It obviously affects load carrying capacity, but it's still plenty strong if you are smart about it.
Sidenote "Kallax enjoyer" is a great thing to from an identity around and I'm updating my Twitter bio as we speak
> I can just remove some of the dividers
How it's better than that: you can not only rotate them 90 degrees, but you also move the dividers. Now due to how their built, it may not be the sturdiest thing to do but you definitinely can turn a 2x 32 cm into a 1x40cm and 1x24cm. I do that for my PC tower (and the wife's): it's too tall to fit in 32 cm, but then I don't want to waste space. I simply make new holes for dowels (once again, YMMV but I do it since years) and move a divider up.