What are the copywriting laws / rules for reproducing and selling original artwork?

For example, can I repaint a masterpiece (The Mona Lisa for example) either in my own style or ‘exact’ replica and sell this without breaking any laws? Clearly, I wouldnt advertise it as an original, it would be stated that it has been painted by myself
Thanks

It’s been done thousands of times. If you make a ‘study’ of a famous painting and give it your own signature that should be fine. Copyright rules do vary from country to country and are extremely complicated.