I do the same. All you need a boost power supply that takes the 12vdc and converts it to 19vdc. Many available on Amazon. Since you are going from DC to DC, there is no need for and inverter.
If the laptop is a dell you need more that a simple DC supply, or it will refuse to charge the battery. The dell-compatible supplies communicate with the computer using a 3rd wire.
Even though most laptops are 19v, some will charge the battery with 12v directly.
Key term is SOME. These are the laptops with charging circuits that are not fussy about the correct input voltage and probably have very little protection.
This is not ideal though because the amount of power consumed by the computer is likely more than it would charge by.
Charging with a designed 12v to 19v charger or using an inverter is a safer option.
USB-C charging is a great feature if your laptop has it.
Even though most laptops are 19v, some will charge the battery with 12v directly.
Key term is SOME. These are the laptops with charging circuits that are not fussy about the correct input voltage and probably have very little protection.
This is not ideal though because the amount of power consumed by the computer is likely more than it would charge by.
Charging with a designed 12v to 19v charger or using an inverter is a safer option.
USB-C charging is a great feature if your laptop has it.