The search tool for GIMP is Google. How do I draw a rectangle? Google brings you to https://docs.gimp.org/2.10/en/gimp-using-rectangular.html which starts with "GIMP is not designed to be used for drawing." and then goes on which "However, you may create shapes by either painting them using the technique described in Section 14.1, “Drawing a Straight Line” or by using the selection tools"
At that point you realize that what you really want is MS Paint from Windows 3.1
At that point you realize that what you really want is MS Paint from Windows 3.1