The computer in question is not hooked up to the internet, nor do I plan on hooking it up to the internet. Is there a way to install Libre Office on a computer that is NOT hooked up to the internet? Have NO plans to hook it up to the internet. The computer in question has Windows 7 OS…
Certainly!
If the target computer is not connected to the internet, you need to bring the installer file to hat computer by other means. The most likely is a USB stick. Installer file for Windows is just short of 300 MB, so it will fit on any media you are likely to use. (CD/DVD/USB-stick, memory card). At some point you need to download it, so you need internet connectivity on some level. As you are posting to this place, that should not be a problem 
The installer for Windows is self contained. There is no progressive download, dependencies, licensing procedure or other conditions requiring that the computer be connected to the internet.
I have the same need. I downloaded the .msi file (choosing 32 bit because a computer running Windows 7 is almost certainly 32 bit). As I copied it, a warning came up asking whether I wanted to copy it without its properties, because not all of the properties could not be copied. This concerned me. This link https://appuals.com/are-you-sure-you-… says: "the file itself will remain intact and functional. That being the case, it is completely safe for you to, when faced with this popup, click on Yes and copy/move the file in question without some of its properties. "
I see other options such as “portable versions” “flatpak” and “snap” I don’t think that any of these are what someone in this situation should use. When I tried to read about them, the information assumed that I already knew what lots of other things were. 
which I didn’t. Are one of these options better?
Don’t worry about losing file properties. They are not needed for the installer to work reliably.
A portable version is good for those who move around different computers a lot and never know which software is installed on the computer. It can run from portable media (a USB stick) without installing software on the computer. Since it is not installed, it does not always integrate so well with other software, networking and other system components. You most likely don’t want that.
AFAIK, snap and flatpak are software distribution systems for linux, with strategies somewhat different from traditional package/dependency and access rights management. For Win7 you certainly don’t want that.