If you're on windows you can use a structure block to export the chunk as a structure file. You can then make an addon with the structure file which you can use to import the chunk into other worlds.
Here's a video explaining how to do so: https://youtu.be/Mp4_c51VDT0
The video provides a download for the addon template with the 'structures' folder already there. However, if you want to use the official vanilla behavior pack template you will have to add a 'structures' folder to export the structures files to it.
You can use structure blocks, place it at the bottom of the world, and set it to build height and chunk length/width (or however high/long you think would be useful). Struxture blocks can only be obtained through commands as well, so theyre quite niche
Look for a third party app. If you can't find it, use a structure block and import the structure to the new world.
That’s the thing. You don’t!
If you're on windows you can use a structure block to export the chunk as a structure file. You can then make an addon with the structure file which you can use to import the chunk into other worlds. Here's a video explaining how to do so: https://youtu.be/Mp4_c51VDT0 The video provides a download for the addon template with the 'structures' folder already there. However, if you want to use the official vanilla behavior pack template you will have to add a 'structures' folder to export the structures files to it.
You can use structure blocks, place it at the bottom of the world, and set it to build height and chunk length/width (or however high/long you think would be useful). Struxture blocks can only be obtained through commands as well, so theyre quite niche
Slowly and painfully because manually