Does it take an Admin to override Check Out?

I have half answered my question.  I have opened Library Settings > Manage Files which have no checked in version (you need to be viewing Documents to see Library Settings).  I was prompted to request permissions to view this option.  I thought this request would go to Global Admin, but strangely, it went to one of my colleagues.  I find this strange, as I thought I was listed as an owner of the site, but he accepted it, and I received an email "Administrator has responded to your request, Good news. You now have access to ...".

Now that I have access, I see a list of all Checked Out Files.  Instead of choosing to override checkout (check-in/discard), it appears I have to Take Ownership of a file.

I am guessing this takes ownership of the pending changes, rather than the last checked in file.  Not quite what I had in mind, but it is a workable solution.

This would answer my question, but I have since found a file that is locked by check out from SHAREPOINT/system.  This file is not shown in the list of Checked Out Files, and so I am trying to find a way to contact the elusive Global Admin.

NB the file is MP4, I can see properties of Duration, Bit Rate, but I cannot open in Teams as it is reported as having no content, and Chrome just says that the video can't be played.