A mod that:

• Increases maximum structure size to 512 blocks
• Optimises the corner search algorithm
• Removes the Jigsaw depth limit
• Removes the 128 block distance limit from structure features/pools
• Adds a creative item group for structure block items.

You can get the latest release from:

• GitHub
• CurseForge
• Modrinth

Just plop it in your mods folder. You now have huge structure blocks of up to 512 blocks!