How can I edit the end's dimension file so that I can add new biomes?

Currently the end dimension file looks like this:
{
  "type": "minecraft:the_end",
  "generator": {
    "type": "minecraft:noise",
    "biome_source": {
      "type": "minecraft:the_end"
    },
    "settings": "minecraft:end"
  }
}
But I want to add a biome or two to the end, how can I do so?