Yes a laptop computer can be overclocked but it's really not recommended to overclock a laptop unless you want to damage the laptop due to overheating.
A laptop can overheat much more easily than a desktop computer because there's not as much ventilation and airflow like there is in a desktop computer.
The parts in a laptop are also more tightly packed in than in a desktop computer which makes the overheating happen much more quickly.
If you do overclock your laptop computer it will void the warranty and will almost always damage it pretty quickly so unless you have an older laptop computer that you do not care about then I would not overclock it.
If you want to overclock a computer I would use a desktop computer with enough airflow and fans to keep it cool.