Which version of VSCode are you using, and in which OS?
On Mac, and with 1.65.2 (the most recent update by now), I have it in the right corner, near the X button:

Shortcuts
Now talking about shortcuts to make your life easier, there are 2 you should be aware of.
PS: Remember that to change any shortcuts, just go over VSCode Command Palette and type Keyboard Shortcuts to change them.
Maximise panel size
There are no default shortcuts for those, in both Windows and Mac.
If you want to set any, the name of the shortcut is View: Toggle Maximized Panel:

Increasing / decreasing terminal size
Now talking shortcuts, if you want to resize your terminal window, in Mac there's a native shortcut that allows to increase / decrease terminal size with Cmd + Ctrl + Arrow Up / Arrow Down.
There's no default for Windows.
If you want to set / change those shortcuts, they are called Terminal: Resize Terminal Down and Terminal: Resize Terminal Up:

Terminal panel on the side
If you added your panel to either left or right, then the mark to make it fullscreen changes.
After clicking on the arrow below, it'll hide all your files and make the terminal to run in the whole screen for VSCode:
