my iphone 13 pro max 256 gb is not showing pro res in camera setting

go to Settings > Camera > Formats, then turn on Apple ProRes under Video Capture.

• Then to record a ProRes video, tap ProRes   in the Camera app, then record your video.

You can activate or deactivate ProRes in the Camera app itself when the camera mode is set to Video. See image below:

You can Tap on ProRes to Activate/de-activate it.

Axel F.