Having a menu bar full of apps is a common problem on macOS, and for a while, the agreed upon solution was Bartender. However, the problem with Bartender is that it's grown quite substantially over the years. So if you just want to a quick way to clean up your menu bar, it's probably not the most suitable product anymore.
Thanks, to Superbits (and ldstephens for the tip), there's a new app that addresses the problem in the most minimalist way possible, Hidden Bar.
It's a totally free app. And all it does, is add a separator icon to your menu bar, which you can place to the right of the icons you want to hide. And then another icon that you can use to toggle the visibility of those extra icons.
There's also an auto-hide preference, so after expanding, they will automatically hide after a specified number of seconds.
It's literally a perfect solution for a very common problem. And it doesn't come with any kind of bloat at all.
I love these kind of apps.