I am trying to build a slide show. I have it built and saved as an odp file. But when I click on the file it opens it up for editing. How do I get it to run as a stand a lone slide show?
Run the slideshow with F5 (or start slideshow).
If you want to play only you can save it as an autoplay format (my advice, stick with the odp format).
As described in command lines options (available with soffice --help), there’s --show argument that starts an impress presentation. There may be a context-menu entry for that in some desktop managers (e.g., “Play” entry in Windows right-click menu).