Object detection models return bounding boxes. These boxes indicate where an object of interest is in an image. In many models, such as Ultralytics YOLOv8, bounding box coordinates are horizontally-aligned. This means that there will be spaces around angled objects.
You can retrieve bounding boxes whose edges match an angled object by training an oriented bounding boxes object detection model, such as YOLOv8's Oriented Bounding Boxes model.