MacOS – How to turn off “Show Bluetooth in menu bar”

I think you are looking for this option:

Here's how I did it.

I installed an app called Magnet which is a neat Window manager for MacOS. It brings Windows' neat Window snapping feature to MacOS and lets you designate how much of the screen a window should take up. One of the modes it has, "Maximise", actually resizes a Window to fill the screen without fullscreening it.

As you can see the results are pretty good. The one down side of this approach is that using Magnet to "Maximise" a window doesn't create a new desktop Space like MacOS fullscreen mode does, but you can manually create a Space using the mission control spaces bar and maximise the app there with Magnet. You can then use Mission control to move this Space around with Mission Control as normal, but it will have a generic name like 'Desktop 2' etc