iPad 6th gen fails to update iOS 15.6.1

What happens when you try?

Does it issue an error of any kind? If so, what does it say?

Make sure you are connected to a strong Wi-Fi network during the update.

Link-> If your iPhone, iPad, or iPod touch won't update - Apple Support

It simply says the update failed, try again.

Then try again later.

Also, try to connect to a different Wi-fi network, and see if it works.