Is there a way to change the background of Minecraft worlds without mods?

Is there a way to change the default background of e.g. the overworld?

E.g. if you choose floating isles they'll have half the background dark, down until eye level. If you want that none of the floating isles background is dark but the same as in a usual overworld, how can one edit that, e.g. can you edit the world file? And vice versa, if you wanted a dark background to eye level in a usual overworld for instance. Or if you wanted a background that looks like in the End.

A different example a bit is that higher than ~ Y 2050 everything except the background becomes black/shadowy, obviously that's a kind of space border. E.g. the block that you're holding becomes completely black. You can see this also when a world loads, right when entering it. Can this "space border" be edited so that it's either not there at all or at a different altitude somehow?