I've read 20-30% more are okay
My laptop also has very good cooling
Just start with 5% and slowly work your way up then you will see how your laptop reacts
Overclocking a laptop doesn't make a lot of SENSE.
Especially if you don't know which confi and which model you have.
To be honest, a laptop CPU wouldn't overclock at all if you didn't have a 2000 euro gaming piece
But overclocking a laptop is possible, but doesn't make sense to me. You get a desktop PC for this