Side remark: on Gimp 2.10, O-L-A is less useful because the same thing can be done with the unified transform tool:
- Decrease the preview opacity so that you can see both images
- Move the top image to make the first pair of reference point coincide
- Move the "Pivot" to that reference point and lock it with the Pivot ➤ Lock option
- Check the From pivot ➤ Scale option (or use Ctrl)
- Check the Constrain ➤ Scale option (or use Shift)
- Rotate and scale the top image to make the second pair of reference points coincide.