STOP IPAD FROM ASKING TO UPDATE SOFTWARE

In Settings General, Software Update, toggle OFF automatic updates.

In Settings app, General, under iPad Storage ( not sure which iOS version you are running on this iPad ), look for any iOS/iPadOS upgrades/uodates in the list of things that get generated.

If you see an iOS/iPadOS upgrade/update listed, tap the gray ( or black ) arrow and delete the upgrade/update.

Then,

For older iPad models with a Home button, do a simple hard reset of your iPad by holding down both the Home and sleep/wake/power button simultaneously until your iPad goes to black and restarts with Apple logo, then release the buttons.

The iPad iOS/iPadOS notifications should be less frequent, but may still appear from time to time.

There is NO WAY to completely disable iOS/iPadOS upgrade/update notifications.

Best of Luck to You!

You should look to update your iOS device whenever possible. Apple's updates are important for security features as well as providing you with the latest features.

These updates help your phone working, I understand updating your phone can be time-consuming, but without them, your phone may cease to work (Some apps require later version of iOS), your device will also be prone to be exploited by hackers and scammers, which still could be a big problem even if you do only use the device to watch movies.

You are able to set your device to update automatically overnight, this means you will not be without your iPad as it can update while you are sleeping.

Update your iPhone, iPad or iPod touch – Apple Support (UK)

Ultimately if you’re ok with your iPad not having at minimum the important security updates needed to protect your data then that’s your right but you will continue to be alerted. As already mentioned (and is actually a helpful suggestion) you can have it auto update when not in use so that you aren’t actually losing time. Again, you don’t have to do it if you don’t want to but you also shouldn’t be upset if/when a security breach occurs and affects you. Right now you have the option of doing iOS 14.8 which is just a security update (although if you haven’t updated in a long time it may be a bigger update for you) versus the new iOS 15 update. By doing 14.8 that should stop the alerts as iOS 15 isn’t required where 14.8 was strongly urged due to the security issue.

Good luck with whatever you opt to do.

It's your iPad.'

You can do what you want with it!

Don’t let anyone tell you differently.

I felt iOS 11 through iPadOS 13 were garbage and I waited it out 3 years before I, eventually, upgraded all of my iOS/iPadOS devices to iOS/iPadOS 14.

But, iPadOS 15 is NOT looking great to me, currently.

So, I am going to wait it out for some more significant point updates to see how iPadOS 15 pans out, for a while.

Best of Luck to You!

If the Poster has never upgraded/updated this iPad ever, it may be too far behind in iOS/iPadOS upgrades/updates, now, and will, probably, need a full computer to do an iPad OS upgrade, now.

Which IS going to be more of hassle for the Poster.

How is that reply “not helpful”? You’re using a computer here. It’s going to need updating sometimes, to maintain security from exploits and malware, if nothing else. This is neither new nor unusual.