Why is there no significant change in model size after pruning and quantization?

[Pass-O-Guava]

Why is there no significant change in model size after pruning and quantization?

For yolov5n model, I ran the training and export python script and found best.pt 7.4M, best.onnx 2M, however, the original model yolov5n.pt 4.1M.

Why .pt model changed from 4.1M to 7.4M, and why .pt model converted to .onnx model from 7.4M to 2M?

Looking forward to someone's help to answer the reason for this, thanks!