My iPad Air 4th generation won’t force restart

"Hard Reset" does not appear in Apple's lexicon. Perhaps you refer to a forced-restart?

Force restart iPad (models with Face ID or with Touch ID in the top button)

If your iPad doesn’t have the Home button, do the following:

1. Press and quickly release the volume button nearest to the top button.
2. Press and quickly release the volume button farthest from the top button.
3. Press and hold the top button; do not release the button until...
4. When the Apple logo appears, release the top button.

Force restart iPad (models with the Home button)

• Press and hold the top button and the Home button at the same time; do not release either button until...
• When the Apple logo appears, release both buttons.

It’s not clear what “hard reset” means. Try this.

If your iPad won't turn on or is frozen - Apple Support