Whatever the reason, installing macOS High Sierra might suit perfectly. Another useful feature that might really help is Stacks, it organizes and turns mess into a clean desktop by putting files and folders into one according to them. Though macOS Catalina has all of the macOS Mojave features and a lot more than those features, even new features especially Dark Mode which most loves. Another reason which might have stopped you from upgrading or installing macOS Mojave or macOS Catalina is its performance. Now for installing that, you will probably need a macOS High Sierra One of those reasons which might have stopped from the upgrade to macOS Mojave or macOS Catalina is its compatibility.
