Is it possible to git clone existing git p4 repository so it will be possible to use git p4 for the new repository?
Here is the usecase: I have desktop PC with full repository cloned from perforce (git p4 clone <somepath>@all) an want to clone it to laptop without touching p4 server (link to it is wery slow and laggy) an be able to commit changes to perforce. Ideally it would be great to use git clone --depth and sparse clone to reduce laptop disk usage.
No. git p4 works by syncing up with a Perforce checkout (it's a wrapper around some p4 commands), so you also need to have the Perforce checkout accessible.
You could clone the Git repo to your laptop, do your work, push your changes to that Git repo, and run git p4 from there when you're ready to submit your changes.