Activate minecraft cheats in survival mode mc?

I deactivated the cheats at the beginning of my survival world

does anyone know how to undo that

Java Edition?

There you can only activate it temporarily by opening the world in the LAN and allowing cheats there

In Bedrock Edition you can do this anywhere in the game settings

It goes as far as I don't know, but you could create a new world with cheats and copy the world regions into the folder of the world.

I would recommend you simply create a new Minecraft world with activated cheats. (Go to "Other World Options" and then click "Allow Cheats")

However, if you want to play in the same world, you can use the NBTExplorer program to change these settings, or you simply select the world in the menu and then click on "create new", then a world is generated with the same seed ( Game progress is lost)