I have the same computer, and the Scale to Fit Below Built-in Camera option is certainly there.
One question that some people run into: When you chose File > Get Info, which was selected: The Adobe Lightroom Classic folder, or the Adobe Lightroom Classic application inside that folder? Because the option appears in Get Info only when the application, not the folder, is selected.
More clues: If you correctly selected the application, above the Scale to Fit Below Built-in Camera option you will also see the Open in Rosetta option. And if you see a Shared Folder option instead, you selected the folder, not the application.