I am not able to take a screen shot on my iPad Pro 10 I am not holding the button down to long

By far the easiest method to trigger and save a screenshot is to set-up and use the corner-swipe gesture:

Settings > Multitasking & Gestures >

• Swipe Finger from Corner - set to ON
• Bottom Left Corner > select Screenshot or Quick Note as required
• Bottom Right Corner > select Screenshot or Quick Note as required

Once enabled, you can easily capture a screenshot with just your finger. Just swipe diagonally from the lower-left or lower-right corner of the screen towards the centre; this will immediately trigger the screenshot.

You can also trigger a screenshot using an Apple Pencil:

Settings > Apple Pencil > [Pencil Gestures]

• Bottom Left Corner - select Screenshot or Quick Note as required
• Bottom Right Corner - select Screenshot or Quick Note as required

The other ways to trigger a screenshot from an iPad are described here:

Take a screenshot on your iPad - Apple Support