I want to realize that every user who logs into the vault will have his own KV directory to store his own secrets. There is no need for everyone to create a separate directory and grant permissions. Is this available?
The user folders will not create automatically, but you can implement a policy that allows them to create it themselves or you can pre-populate a dummy/welcome secret at user provisioning time.
Have a look in Example 8 in my guide for an example policy for users to have their own folder: