What are the commands for the LAN world?

Solution 1:

All the commands are available when you type / and keep pressing Tab. It will loop through all available commands. And if you are good enough, you can figure out what a command does and how to use it by judging from its name.

You can also use the command /help <page>. It will show you all the commands available with a simple description. You can also do /help <command> to show the specific help of a command.

There's no explicit need of looking up the Minecraft Wiki every time you want to use a command unless you are really messed up and need some clarifications on the commands. I believe a quick glance of the wiki page will be enough.

Solution 2:

All the commands are listed on the wiki, along with which game modes they work in.