You are correct that you will need a separate field to display the colors.
You will need to make a formula-text field. Then use a "Case" formula to display the appropriate image.
Something like this:
Case([Status],
"Green", "<img src=\"
https://images.quickbase.com/si/16/228-rect_green.png\"; alt=\"Project Status: Green\" title=\"Project Status: Green\">",
"Yellow", "<img src=\"
https://images.quickbase.com/si/16/229-rect_yellow.png\"; alt=\"Project Status: Yellow\" title=\"Project Status: Yellow\">",
"Red", "<img src=\"
https://images.quickbase.com/si/16/227-rect_red.png\"; alt=\"Project Status: Red\" title=\"Project Status: Red\">",
"")
