RealisticWorldGenerator allows you to easily generate a really cool looking world. Oraxen is not supported by the plugin (this means that the plugin does not contain any specific code for oraxen, allowing you for example to use Oraxen items in the default loots like dungeons, villages, etc) but this supports custom BlockDatas, so you can add custom minerals created with Oraxen to be generated like diamond for example.
Spigot Link: https://www.spigotmc.org/resources/epicworldgenerator-1-15-1-16-4.8067/
How to create custom ores
In this example we assume that you have added a block (an amethyst ore for example) following this example to your oraxen configuration.