If you got dedicated graphics in your system: It cannot can exceed from its max default unless you overclock it, but not also not all laptop gpu can be overclock... if ever, it is highly not recommended since cooling system of laptop is not so versatile as in Desktop.
If you got Intel HD graphics / shared gpu memory: Laptop usually do not have bios setting to select desired amount of shared gpu memory with ram, unlike Desktop. Since you are using laptop, most likely you won't be able to increase the amount of graphics memory. But there are ways to optimized shared gpu memory..