Open the world you want to enable cheats for
Go to the world settings (Java: “More Options”; Bedrock: “Edit”)
Turn on “Allow Cheats” (Java: “Allow Cheats: ON”; Bedrock: “Cheats: ON”)
Create the world (or save the changes)
In the game, open the command console
Type a command starting with `/` (example: `/gamemode creative`)
Press Enter to run the command