After you set up the database replication and configure the Geo nodes, use your closest GitLab node as you would a normal standalone GitLab instance.
Pushing directly to a secondary node (for both HTTP, SSH including git-lfs) was introduced in GitLab Premium 11.3.
Example of the output you will see when pushing to a secondary node:
$ git push
> GitLab: You're pushing to a Geo secondary.
> GitLab: We'll help you by proxying this request to the primary: ssh://[email protected]/user/repo.git
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