You may be able to change the hard drive for a larger or faster one, or you can plug in an external hard drive. You might be able to increase the amount of RAM. That's about it. You cannot readily change the CPU or graphics.
Laptops are portable and lightweight. The cost for those advantages is that they are not really upgradeable. If you want an upgradeable machine, you should build a desktop system - they are modular, and you can upgrade them piece by piece.