How to increase the graphics and increase FPS without heating

There really isn't any hardware upgrade path for phones. Once you buy it, you have what you have, so if you want a faster phone or one with better graphics, your only choice is to buy a different phone. Desktop computers were made up of separate components that were made to be replaceable, so you can simply buy a better graphics card or add more memory, but that's not true of cell phones. Like laptops, they are made to fit a very limited space and to do so replaceability of parts is generally sacrificed to conserve real estate.

So the short answer is, unless you find some magic software solution your best bet is to sell your phone and use the money to buy a better one.