How do you activate bedrock's offhand so bedrock players can place any item on it?

[blazing plume]

I don't know how to activate it, can anyone tell me how to do this?

[bitter palm]

sadly, that's not possible - it's a client limitation. However,you can switch the item in your hand with the item in your offhand with the /geyser offhand command

[tired cove]

Is it always there or do u have to configure it or sum

[bitter palm]

The geyser offhand command is built in.

[sand rain]

Offhand slot can also be configured to be swapped when emotes are used, and/or disabling emotes