I’m not proposing this as an actual solution, it’s just a dumb idea. But if we dug a huge, wide hole at the bottom of the ocean, or maybe widened the Mariana Trench or something, could that extra space make the sea levels drop enough to keep the land from flooding?
Not if it was deposited on bedrock, or even if it wasn’t if it was done in a way that works with the currents. There are many examples of artificial islands being built successfully.