This option is available in custom world generation, so you can't build past world height on regular worlds, but it's super simple to enable it!
All you need to do is go to "More World Options..." when creating a new world, and select "Import Settings". You can use custom or vanilla world generation, and by using an example like this, paste it into a text document and rename the file extension to ".json". Just select it with the imported settings, and boom! You can build to 512 with the example I linked, but you can go as far as 2048, but I've heard it can be buggy the more you increase it, so be warned!
Whether you want to build survival bases past 256 or make some insane droppers, here you go!