Ah if you want auto completion for native commands they need to be registered first. PSReadLine provides autocompletion support but it only works by default with things builtin to PowerShell itself. For `git` there is a fairly popular module called posh-git [1] that provides auto completion support for some of the well known commands. Git for Windows also calls it out [2]. You can also provide your own custom auto complete calls with Register-ArgumentCompleter [3]. Hope this helps!
[1] https://github.com/dahlbyk/posh-git [2] https://git-scm.com/book/ms/v2/Appendix-A%3A-Git-in-Other-En... [3] https://learn.microsoft.com/en-us/powershell/module/microsof...