Once in the Nether, fully charge a respawn anchor. Then, kill yourself 5 times until you respawn in the overworld. Once in the overworld, use any type of sword and left click a block. The block either disappears, turns into netherrack, or turns into crimson soil, shroomlight, crimson stem, or nether wart block. If you die again, all the blocks effected will turn int their default state.