Fn+F does the job! It will maximize and minimize to a full-screen application.
Answer from Rob Kley on Stack Exchangeand what causes this?
for reference, all of these windows have the yellow circle between red and green clickable.
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Fn+F does the job! It will maximize and minimize to a full-screen application.
Using macOS 15.2 Sequoia here.
The menu item window->fill, defaults to ⌃F (Ctrl+Fn+f), should do what you want.
The item window->center ⌃C (Ctrl+Fn+c) restores the original size and centers the window.
Menu item window->minimize ⌘M (Cmd+m) minimizes the window.
To remove the spacing around the "filled" window, you have to go to System Settings -> "Desktop & Dock" -> disable the option "Tiled windows have margins"
Hi all. I’ve looked this up but can’t seem to find the solution.
I would like to have all my windows maximized when I open them, in any application on my Macbook (Monterrey). I don’t want to open them in full screen, but just want them to always open maximized. Can anyone help me out?
One of the default settings in System Preferences > Dock is [√] Double-click a window's title bar to zoom; however by default, e.g., Finder does not have a keyboard shortcut to zoom a window.
One may add a keyboard shortcut for the Finder > Window > Zoom command in System Preferences > Keyboard > Shortcuts > App Shortcuts, as shown in the image below.
Note that one can also choose All Application and use the following as the menu title,
e.g. Window->Zoom so as not to confuse it with another Zoom command elsewhere in its menu system if applicable.
Have a look at: Create keyboard shortcuts for apps on Mac
Click the [+] and fill in the sheet, then click the Add button:

The previous answers do work, of course. The problem is that sometimes maximizing the window isn't the same as having the window full-sized on your desktop.
There is an app on the Mac App Store called "Magnet" (https://apps.apple.com/at/app/magnet/id441258766?mt=12) which does this job perfectly and you can even customize the shortcuts.
Just like command + tab, but to a specific app only.
Like, press F2 to minimize/maximize my task app.