How to add OPs (operators) to your Minecraft server

[
  {
    "uuid": "Your-UUID-here",
    "name": "minecraftusername1",
    "level": 4
  },
  {
    "uuid": "Another-UUID-here",
    "name": "minecraftusername2",
    "level": 4
  }
]

Minecraft Permission Levels
level 1 (moderator) - Player can bypass spawn protection.
level 2 (gamemaster) - Player or executor can use more commands and player can use command blocks.
level 3 (admin) - Player or executor can use commands related to multiplayer management.
level 4 (owner) - Player or executor can use all of the commands, including commands related to server management.

You will need to replace the values with your names and with your UUID. There are numerous ways to find a UUID. Mojang provides an official API to find one by simply providing a display name. Take this URL below, and change the end where it reads "Username" to your actual Minecraft name:

https://api.mojang.com/users/profiles/minecraft/username

The link will then provide you with your full UUID.
Once you've edited the file accordingly, save it and you should be all good to go!