You can technically build anywhere and use /fill to flatten the land out. Know that the /fill command can only build squares or rectangles.

You will be inputting these coordinates into the /fill command. You can also pull up your coordinates by pressing the FN and F3 keys at the same time.

You could also do this with a cube. For example, if you’re standing at the back top left corner, move to the front bottom right.

You can also do /fill ~ ~ ~ to fill from the first set to where ever you are standing without manually inputting coordinates. is a stand-in for what you’re going to do in the next step. Don’t type it in the command. Don’t submit the command yet either.

You can also type “minecraft:” and then hit tab until you see your block. You can type the first few letters of your block (like you would while searching for it in the creative inventory) and hit tab to narrow down the search.

hollow: makes the inside of the rectangle hollow replace: replaces all blocks of one type in the area with another, ie /fill <set 1> <set 2> minecraft:diamond_block replace minecraft:clay destroy: not only replaces all blocks, but breaks them and turns them into items you can pick up as if they were mined) keep: fills air and leaves blocks inside the rectangle unaffected outline:outlines the blocks already placed with the block you choose

This is an example of a correctly typed command. Be sure to have the /fill, the two sets of coordinates, and the block you wish to use. Example typed: /fill -299 64 -110 -334 79 -138 minecraft:diamond_block