I discovered the Hugh Structure Blocks mod and tried it out. However, I had to realize that if I want to load a previously saved structure (24x300x24) this does not work and it only loads 24x30x24 of the structure and thus a large part is missing.
I'm not sure if it's intentional or not.

Minecraft 1.21 and fabric-loader-0.16.5
huge-structure-blocks-1.1.2-fabric