This method is the easiest as you can make a copy of your Google Slides presentation directly from the presentation file when it is open!
Click on the “File” tab, From the dropdown menu, select the “Make a copy” option which will open yet another drop-down menu. Now select the “Entire presentation” option.
After you click on the “Entire presentation” option, a pop-up window will appear. Simply click on the “OK” button and a copy of your presentation will be saved on your Google Drive.
In case you don’t want to copy the complete presentation, you can also make a copy of a selected set of slides and open them as a separate presentation file.
Click on the “File” tab which will open a drop-down menu. Next, select the “Selected slides” option from the drop-down menu.
After you have selected the “Selected slides” option, a pop-up window will appear on your screen. You can rename the presentation. This is completely optional. Next, click on the “OK” button.