Just stumbled on this app, “Hyperkey”. It’s 4.99. It’s exactly as it sounds. It replicates the famous Caps Lock → CMD+OPT+CTRL+SHIFT modifier (normally done with Karabiner) within a nice GUI. There are also some added niceties that some might like, like the ability to create a “Hyperkey” gesture on the trackpad.
I’m still using Karabiner Elements because I also map Caps Lock to some VIM navigation shortcuts, but this is a solid route to go if you don’t need that control. Much easier than trying to figure out Karabiner.