Wake on Ethernet or WLAN. Didn't have success with the latter. Apparently the Qualcomm Atheros Wifi chip from 2018 wasn't compatible or something.
P.S. Why keep the lid closed in this scenario? It will result in worse thermals and increased wear and tear of the hinges.
Go into the BIOS/UEFI set-up. Under "Power Management" there should be a "Wake on AC". Enable it.
What that means is that the moment you switch on the power adapter connected to your laptop, the laptop will boot up. I am typing this on a monitor connected to an IBM ThinkPad with its lid shut 😊