This is mostly because the rating on most cig lighters are 12v @ 10a. That is 120Watts.

You are better off getting a power station like this: https://www.amazon.com/BLUETTI-Portable-EB3A-Recharge-Generator/dp/B09WW3CTF4

It will hold more than enough to charge your laptop a few times. Do you know if your laptop can charge via usb-c PD? If so you won't even need the power brick for your laptop.

If you are really worried about draining the power station, buy this as well: https://www.amazon.com/GINTOOYUN-Cigarette-Lighter-Bluetooth-Speakers/dp/B09JKMHMGW

You can then use the cig lighter to charge power station.