Want to clarify things first.

I have this function and I will use the set jwt token. Now the client side will pass a jwt token for that cloud function I want answers for all this questions:

In server side if I account.get. I can get the user info even I am in the server side right?
I am going to create documents and set a permissions to the specific user, not himself/herself. Because in client side when I try to set a permission to referred to another user it gives me an error, so In server side can I able to do this ?

TL;DR

The user wants to clarify a few things. They ask if the team will implement a feature to set permissions for someone else in the future. They also mention that the client does not need to pass a JWT and that certain headers are automatically filled when the user is logged in. They question why they need to call account.get() and mention that using a JWT is the same as making the API call client side. They mention that to set permissions for someone else, an API key should be used. However, they are facing errors when trying to create permission for another user. They plan to use a JWT token instead of the API key

I can't parse the first part of your question, but the 2. - yes if you have a privileged API key.

But then it also works from the client

I will use jwt token insteaf using the api key.

I am getting error when I am creating permission specific user excluding self id, for example User B will have permission to write this document. IN that case it will throw an error

But nvm

https://discord.com/channels/564160730845151244/1159597446444368022

Using a JWT is the same as making the API call client side as the user.

If you want to set permission to someone else, you must use an API key

Btw, the client doesn't need to pass a JWT. If they're logged in and they execute function, 2 headers are automatically populated with the user's id and JWT. See the docs.