how to use 64mp with libcamera:
How to use arducam_64mp & arducam_64mp FAQ - Raspberry Pi Cameras - Arducam Camera Support Forum
How To Use Arducam 64MP Camera On Rapberry Pi - Arducam
You can display the obtained data with opencv, but you cannot get the data directly with opencv.
You can refer to picamera.
picamera2/examples at main · raspberrypi/picamera2 · GitHub