I am trying to set up a preset rectangle size for landscape(1600x1200px) and portrait images(1200x1600px) so that I can position my preset over the image to the exact area to be cropped. I have tried and tried but am lost. Help is greatly appreciated. Gimp 2.8.22

Not difficult: see the screenshot

(1) Choose the crop tool and in the tool options set up the way you want. Fixed and select size from the drop-down. Put 1600x1200 for the size & landscape or portrait icon (does not matter much - can be changed in use). Then Center lines if you want. (2) Click on Save Tool Preset
(3) That opens the preset dock. Give the preset a name. (4) Click on Save and then close the dock

In use:

(5) With an image open. Click on Restore Tool Preset. Choose the 1600x1200 option.

Click in the canvas to open the crop tool. Change landscape / portrait in tool options. Position the crop and enter to apply

FWIW a quick Gimp 2.8 demo: https://i.imgur.com/dnUxynn.mp4

I thank you so much for this detailed explanation. Adding the screenshot and the "how to video" was exactly what I needed. Cheers!!!

Solved:

I am trying to set up a preset rectangle size for landscape(1600x1200px) and portrait images(1200x1600px) so that I can position my preset over the image to the exact area to be cropped. I have tried and tried but am lost. Help is greatly appreciated. Gimp 2.8.22