Adding Debian Bullseye Gnome Window Minimize/Maximize Controls

Enabling

2. 2. Installing GNOME Tweaks

   Then to Install GNOME Tweaks Tool
   Simply play:

   sudo apt install gnome-tweaks

3. 3. Enabling Minimize/Maximize Controls

   Then to Add Window Minimize/Maximize Buttons
   First, Launch the GNOME Tweaks applet:

   

   And then Navigate to Window Titlebars > Titlebar Buttons: