Which took a little while to do. I first downgraded my world to snapshot 21w03a (if I remember correctly) and used a glitch with glow lichen to put water in the Nether. Then I repeated this for an entire lava lake, which took several weeks. Then I mined out the first layer of red nether grass or whatever it's called and replaced it with regular grass. I also added dirt, overworld trees, flowers, tall grass, etc. The entire process took about two months to complete. (And it was all done in Survival Mode).