It's like when I play on my laptop, when the power cord is unplugged, I have the same power as when it's plugged in, and that's not normal, is it?
All a matter of attitude.
Yes, you can set in the Windows energy options whether you want to reduce the performance of your laptop on battery power or not. So you can determine yourself whether your laptop delivers the same power when running on batteries as when running on mains.
Temperature is often a limiting factor in laptops.
Can you please tell me the necessary settings?
The settings should be found under "Energy options".