The examples from the OP are configurable from Tweaks which is a GUI. No hacks, command line use, or third-party installs. In particular, the equivalent to the screen shot you showed is available from Gnome's Tweak tool.
FYI, the Gnome Tweaks interface is basically identical to the KDE settings here.
Screenshot: http://pvv.org/~jabirali/tweaks.png
> I find gnome to be pretty configurable. The opinionated defaults aren’t so bad because you can just replace the environment if you dislike it
IT'S NOT CONFIGURABLE. You can hack your way around their "opinionated defaults" which are for MacOS user from USA.
Take a look at the KDE's settings for this case https://i.stack.imgur.com/ukKmp.png
There is no reason to google, install some tool and mess with it.