You can //pos1 (NW corner) //pos2 (SE corner) //expand 100 100 u (//copy 100 blocks above and below where you //pos1 and //pos2ed), //copy (note where you //copy, that is where it will //paste in relation to you later) //schematic save name.
Go anywhere in the world and schematic load name, and //paste. you'll need a little patience, it can take what seems like forever.
I know WE will work for 1.12.2 and below. I'm not certain there is a 1.13 or 1.14.
You could also use the Litematica mod, which does work with 1.14 and below. Although with any in-game way to save and paste schematics of your builds, it can/ will cause lag. For me personally, trying to paste a schematic that is TOO big will crash the game (but, my computer is on the older side, and the area that causes crashing is pretty huge). I know there is software that can be used to edit maps outside of the game, but I don't know much about them, or what they're called.