If you have only one ControlNet unit go to the Settings > ControlNet and set "Multi-ControlNet: ControlNet unit number" to 2 or more. Click "Apply settings" and restart UI.

In ControlNet unit 0 use Preprocessor: none and Model: openpose. Drop openpose image here and enable it.

In ControlNet unit 1 use Preprocessor: none and Model: canny. Drop canny image here and enable it.

ControlNet mode set to "Balanced" and generate image.

If you want to use img2img (which I recommend) use img2img + ControNet canny with Control Mode "ControlNet is more important".

Resolution for txt2img: 512x768