https://forums.raspberrypi.com/viewtopic.php?t=344067
IIRC (or AIUI) VNC does need X etc and, on a P4/P400 (with Raspberry PiOS 
"Bullseye") a "headless screen resolution" set** (for, as others have stated, 
a display buffer to be created). For "true headless" operation (remote command 
line / terminal only) just change the boot option to command-line only (and no 
auto-login), enable SSH, and connect via PuTTY (or equivalent SSH terminal) on 
the remote machine. (Or even use a serial connection via a suitable 
USB-to-serial dongle to the appropriate GPIO pins). I prefer the "boot to 
command line method" rather than use Raspberry PiOS Lite since my Pi's may or 
may not be (partially) headless (ie. no display, but maybe with a 
mini-keyboard + trackpad/ball attached)

see http://www.cpmspectrepi.uk/raspberry_pi/MoinMoinExport/RealVNC_RaspiPIOS_Bullseye.html

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pi 4.0 HDMI / VNC prob when headless
https://forums.raspberrypi.com/viewtopic.php?t=253312

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force raspberry pi to boot to cli without raspi-config

press CTRL+ALT+F2 then login on /dev/tty2, wait ten minutes, get a terminal

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https://raspberrypi.stackexchange.com/questions/121850/boot-into-gui-by-default-without-raspi-config-command-line-only

Here's the script that raspi-config runs when you enable the GUI without autologin:

      systemctl set-default graphical.target
      ln -fs /lib/systemd/system/getty@.service /etc/systemd/system/getty.target.wants/getty@tty1.service
      rm /etc/systemd/system/getty@tty1.service.d/autologin.conf
      sed /etc/lightdm/lightdm.conf -i -e "s/^autologin-user=.*/#autologin-user=/"

You may need to edit a different config file if you have a different desktop manager.