How to change how you take a screenshot

Having a broken power button is not good!

Without it you cannot ever perform any hard resets of your iPad, if somethng flaky happens to your iOS devices, or to put your iOS device into restore mode, IF something bad happens to your iOS/iPadOS device.

You need to get that Home button repaired or purchase another iPad that has a working Home button.

If something happens to your iPad and the Home button is malfunctioning or doesn't work, you will be out of luck getting tbst iPad back to a working condition.

All of this stated.

The ONLY way to get around this damaged Home button issue is to use the Accessibility features in the Settings app.

Go into the Settings app, Accessibility, Touch, toggle ON Assistive Touch. Customize Top Level Menu.

You can add menu buttons that show up when you tap the Accesibility software, virtual button that appears on your Home screen.

You can set these top level menu buttons to anything.

One of the options is the create a screenshot button.

OR

Another method, once Assistive Touch is toggled ON

Under Custom Actions, you can assigned a Single tap, Double tap or long press of the virtual Assistive touch button to do a screenshot action.

I use the virtual Assistive Touch screen button and have it setup for a Single tap of that software button to return to the Home screen, Double tap for a screenshot and a long press ( of a certain duration ) to activate the Siri assistant.

Good Luck to You!