How do I add items to the Properties Sidebar in Writer?

I’m using LibreOffice (25.2.7.2, macOS Sonoma) to add alt text to a bunch of objects in a .docx file. I can do this by right-clicking on an object and selecting “Properties…” There is also a Properties sidebar that pops up whenever I select an object, which looks like a great time-saver. However … the only “submenus” under it are Area, Wrap, and Position and Size.

How do I add Options to the sidebar, which is available from the popup I get when right-clicking on the object?

(I tried searching for help, but no solutions were ever provided.)