HOW did Rex Lapis fake his death?

New-ish player here. I’m already aware Zhongli is one and the same with Rex Lapis, just wondering if it was ever actually mentioned HOW he faked his death? like he just fell out of the sky… was it ever mentioned in the story if there was more to it? perhaps I forgot or missed it entirely. also does this mean the God of Geo will be replaced? he’s technically not dead, he’s still there so the title should still be with him.