Software update on my iPad

If, as I suspect, you have an iPad 4, released in 2012, it is not possible to update beyond iOS 10.3.3, because it is not capable of running the newer 64 bit architecture required of the newer level iOS. If there are features you need in the newer iOS levels, it's time for a more modern ipad.

What model, year, generation is your iPad? It may be at the latest iOS it is compatible with.