Is it possible to slow charge a 240W laptop with 65W power bank via USB C?

I have a Dell Precision 7750, which has a strong GPU, and therefore a power adapter with 240W. When I'm on the road, I need to charge the laptop with a power bank. My power bank is 65W. I want to charge the computer, even if it is very slow to charge. I don’t want to run the GPU when doing this, so probably the computer does not consume 240W but much less. When I plug the power bank via the USB C Thunderbolt 3 connection, nothing happens, and warning comes up that the PC is not charging. What can I do?

Question by BestR on Super User, licensed CC BY-SA. We show a short excerpt and link to the original thread as credit.