I don't use Xcode itself, but do use the Xcode command line tools. I've found the simplest way to install them on a new machine is to open a terminal, try and run `git` (which isn't yet installed), and then you're automatically prompted to install the Xcode command line tools (only) and taken through it.
I don't know about the reasons of the parent but in my case after some time I was unable to upgrade Xcode on a new MBP 2019 with 128 GB even though it was the only app installed! It was about disk space management when installing via the App Store (not to mention growing space requirements). Downloading it manually solved the problem.
